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.

Do you really have to think about it? Has todays society completely lost it's ability to be civil? When I lived in India as a kid (parents were French translators), EVERYBODY thanked everybody. People were just friendly to each other, for no reason. Have we lost the ability to simply say thanks to somebody like your bus driver?