[corresation]

You were intending to pay for your meal anyway; that you're actually paying for someone elses meal makes little difference for you

These chains have been common at coffee shops drive-thrus in Canada for years, where the standard deviation of orders is very small: Almost everyone is just getting a coffee and maybe a donut. A couple of dollars, generally. I have to imagine that order size varies much more dramatically at a burger shack, and it has to suck if you and getting your cheeseburger and end up in a chain with a family of six behind you.