My Postmates driver is not getting a tip from me.
Do you normally tip? Why aren't you this time?
The Postmates driver drove too slowly
That may not have been their fault. You can't make snap judgements based on no evidence. Especially when it affects someone's income.
Shit, now I feel bad.
It's okay, there is still time to tip this person I'm sure. It's good that you learned this lesson.