Take on the Dunkin Donuts no tipping policy

I can't say I have often tipped at a drive through but today I found
out that at a place like Dunkin Donuts it's not even possible.
Although I can't think of a good reason to do it, I also can't think
of a good reason why you cannot tip. What could possibly be bad
about me throwing $0.32 to a high-school dropout after he delivers me
a large dark roast and leaves me no room for cream and sugar. If you
aren't going to give them a living wage, let me at least throw the guy
enough to not totally afford a Dunkin coffee