People really feel committed to buying something just because they walked in the door? Even if they do, there's no commitment to buying a burger, fries, and soda. But I'm not familiar with people feeling a commitment to buying something in other kinds of businesses just because they are there.
Regarding the bolded: To a point, absolutely.
I mean, if the burger was like $100 ... yeah, you walk away from that. There's a point where you turn away. But the $12 bacon cheeseburger, IMHO, was within a reasonable "
grin and bear it" range for most people. I could, however, see some people looking at the menu and leaving (but then you have to either go through the trouble of finding another place to eat on the spot, or else go home and eat). If you're walking into a Five Guys, you're generally there with the expectation and commitment of eating there, not with the expectation of checking prices first and then deciding whether to eat there.