The primary reason for this is that the cost of space travel, at this point, basically trumps any other cost imaginable. Sure, it's the future, but it's likely that cloning will be perfected sooner than space travel, even now, in the real world. If you took the scenario in the movie and applied it to today, and said that the moon was filled with a renewable super-resource that would solve the world's energy problems, it basically wouldn't be cost effective to send people up there and get it vs. just ignoring it. This is why we generally don't send people into space.

There's also the fact that these guys probably get paid a lot. I mean, if you WERE hiring astronauts, they'd want a pretty penny to be completely isolated for 3 years; in some senses it's no better than jail. Then there's the fact that you would literally have to train every single one -- I can't imagine anyone wanting to make a second trip if hallucination and psychological problems are common among the astronauts. That training in and of itself has gotta be remarkably expansive: from the movie, it seems clear that Rockwell really knows a massive amount about the mechanics of the station, the rovers, the mining machines, etc. etc., so training someone how to operate, maintain and repair all of that stuff is probably years in and of itself. Some of these astronauts would have second thoughts or other issues that would cause them to drop out, as well, so you'd have to be training at least three to five people in case you lose some of them along the way.

Ultimately, the biggest bonus for the company, though, is that Sam is controllable and replaceable. If Sam loses his shit, is injured or has some sort of problem, the company can no doubt just neutralize that clone and pop open a new one, something they could never afford to do with a newly-trained astronaut. There's nobody to answer to if Sam is killed, no liability, no nothing. In essence, he's a better, more effective robot than the company is capable of building.

I'm not a cloning expert but keeping (possibly) hundreds of clones aboard the ship just seems more expensive than sending a human(s) to the moon once every three years. They still would have had to space travel all those clones there in the first place. They would also need some way to keep the clones maintained and alive the whole time. Using one person to run this station would be essentially "putting all their eggs in one basket". If Sam had psychological problems during his trip, it would make sense that his clones might also experience similar issues. Also you could never improve their training. New astronauts means you could learn from past missions and provide better training. Sam's clones wouldn't have learned anything new. Having multiple astronauts would also probably make it safer and less difficult psychologically. It wasn't a total deal killer for the movie but using clones just seemed unnecessary.

clones

Sam 1's deterioration was due to lasting longer than 3 and his body shutting down.

We don't know where the clones were made. If they were made off-Earth, there may have been significant savings over transporting hundreds of humans from Earth.

As for the rest of the issues about clones, you either have to accept the film's premise that clones are cheaper, or not. There's hardly a "definitive" argument that can be made today about how a fictional future's economy works.

Isn't 3 years long enough? My take has been that the original Sam did spend a 3 year rotation on the moon, after which they cloned him. So they had 3 years of video messages from his girlfriend, and the Sam clones have the memory of signing up for a 3 year run. So 3 years was as long as they could reasonable expect to "dupe" a Sam clone.

This is apparently a problem with real-life clones. It's very complicated and I'm probably explaining it wrong, but cells are basically alive and healthy because they've been around for however long they've been around. To cheat and clone someone at a certain age is unstable and eventually collapses. As of right now the only theoretical way someone could genuinely be cloned is way back at the fertilization stage, and then of course, it's barely a clone; more like a twin.

this is exactly what I was getting at when it comes to space travel -- it's just ridiculous how astronomically (no pun intended) the price will trump anything and everything else. I imagine to send someone to the moon every three years costing close to a billion, while each clone costs close to a million. Or even the travel costs $100 million vs. $1 million for the clone. As for the price of sending the clones up there, the clones are all sealed in those lockers; the cost of space travel includes things like food, atmosphere, all of the stuff a human person would need to travel through space. Much easier to send a cargo rocket with a crate full of hibernating clones than to send actual people.

Is there any reason to assume that cost of space travel is the reason for massive clones? Nothing in the movie seems to indicate that being a reason, so it seems like an odd angle to take, any more then assuming a company would be ok with hundreds of clones to reboot over and over again for a hundred years then sending another shuttle eventually. Or just sending a small team rather then a single individual Regardless, the actual reasoning behind it doesn't really bother me anyway.

Where are we the audience in the timeline? I assume we are not seeing the original Sam, correct? When Sam clone, gets into contact with his daughter who is 15 years old, she calls for her dad. We never see him but I assume it would have been the original Sam?

Basically, I think the process is:
"Why clones?"
"Why not clones?"
"Why not people?"
"Clones must be more beneficial."
"How would they be more beneficial?"
"Well, it's a company, and the company is trying to hide it from the clones, it must be a corner-cutting measure."
"Aren't clones expensive?"
"What's more expensive than clones?"

My answer being space travel.

About the cost of cloning vs. cost of space travel - the argument is weakened for cloning when we the audience realizes that there are other people on the moon. If there were no signs of anyone else being on the moon I can buy that, but there were others there on the moon.

There was nobody else on the moon when the accident occurred. The "rescue team" had to be sent to the moon from Earth, which is why it took them so long to arrive. My guess is that, like most short-notice emergency missions, it was an extremely expensive endeavor.

I guess I missed that detail. I thought they were on the other side. Hmmm, thinking about that and knowing that the company had the ability to send people out there in case of disaster regardless of where they come from weakens the film since Sam wasn't truly isolated. The idea that the rescue team is the motive for Sam to get out of dodge or else they'd be killed undermines the first two thirds of the film' atmosphere of Sam having to deal with his problems only by himselves.

If I were a business and had to look at the costs of implementing a clone program to do automaton work, it would be only carried out if it were the only option and because no one could regularly travel there feasibly.

This is a minor criticism of mine since I felt overall it was a superb thriller.

The rescue team takes a few days to arrive, so in an emergency Sam is more or less reliant on himself to survive. Remember that if Sam 2 hadn't been awoken, Sam 1 likely would've died inside the rover before the rescue team arrived (as he did anyway).

Keep in mind that the rescue team was likely sent at great expense. I think that the harvester that was broken from the beginning of the film is a clue. It is possible that this sort of accident happened before, but sending out a rescue team to repair just one of four harvesters wasn't worth the cost, so they left it out of commission. It's only after a second harvester goes down that the company decides they need to send a team to the moon.

I guess it depends on how you define "feasibly." In the context of the film, it seems the company defined "feasibly" as "economically," and decided that the clone program was cheaper than the alternative.

Yeah, I mean...clearly the company knows it's doing wrong. Otherwise they wouldn't go to such great lengths to hide it, and they wouldn't be so patronizing to each clone in the video messages. I mean, sure, you might consider it a last-ditch effort, but then you wouldn't be thinking like the company in the movie.