Thanking the bus driver?

Do you thank the bus driver? If yes why do you do it? Some argue he's not doing you a favor so you shouldn't.

>>7
Doesn't make a difference to the receiving end though, now does it? Even if I say it to the person bagging my groceries, the mailman for hauling up a big box to my door, or the bus driver, it still means something to them after such a taxing deed.