I've worked at a grocery store too. We did get tips once in a while but we were told to refuse them. In the bosses eye he was paying you a proper wage and a tip was insulting him. Restaurant owners do not feel the same way.
Also, you would be surprised what most bosses don't notice in terms of how hard employees work.
Mine thought it was awesome.
Yeah that isn't illegal here. Also it is related to the job.
Customers might not like it because we referred to their homes as trailer parks.
Edit: Crap, just remembered. Apparently my old store switched to a different POS system and all that data was lost
I'm sure the individual drivers still keep track of who tips and doesn't.