I think thanks is a politeness that should be exercised when the situation requires it. I also hate when someone's running for the bus "Wait! Don't leave! Hold on! PUFF PUFF PUFF!" and the driver holds the bus. I can count the number of times people have NOT passed the driver by without even a "thanks mate!" on the fingers of one finger. Really, if that's not rude I don't know what is. It drives me mad!
The guy didn't have to hold the bus for you, you know. YOU were late. He was paying you a courtesy, being nice by making sure you got the bus and you don't even thank him when you get on! Rude ****.
Analyse that! I'm angry on behalf of someone else for a third party's lack of manners!