In America tipping waiters and delivery people is automatic. There may be a few edge cases as you get closer to fast food, but not very many.
The ambiguity runs the complete spectrum here. Many Indians I eat with don't tip at all or leave a token couple of coins even on fairly expensive meals. Others - especially if they have spent significant time in the states - leave the western 10 - 15%.
The weirdness is further intensified for the broad range of prices involved. Like we have a chaiwalla who comes by my place twice a day and pours each of us a small cup of chai for 3 rupees each. I'm not involved in the financial transaction, but I'm sure there's no tip involved.
In contrast the pizza I just ate for dinner was 160 rps. Somehow I felt funny tipping the pizza delivery guy when the chaiwalla guy came and poured us all cups of chai for less than I would have tipped for the pizza, so I dissed him.
But whereas the chaiwalla has probably never gotten a tip from anyone, I have tipped the delivery guy before, so there was anticipation there which wasn't met. I feel guilty about that.
