Wait a second, you can buy your ticket and concessions at the same place? I've never seen or heard of that before.
Doesn't that create longer lines as people buy tickets and then mull over what garbage they want to take to their seats to eat?
At my local AMC, during slower times they combine the concession/ticket lines, but they're separate at peak hours to eliminate the back-up you're describing.
In spite of traffic issues, I'm surprised more theaters don't combine the lines. I can see a lot more people impulse-buying food/drinks if they're standing in a concession line in order to get their tickets.