Either they're infrequent travelers who don't release they're going to have to remove their shoes (whoops - it's *not* a regulation, right? you don't have to remove your shoes, but if you don't you'll get a secondary screening where you *do* have to remove your shoes) or they know they have to remove shoes and want as easy a way to do it as possible.

Either way, it's the rules not the people. And anyone with TSA that thinks otherwise is precisely at the root of the problem.