The problem here is the size of the tip.
You either tip or you don't tip.

If he stiffed them, I doubt anyone would say anything.

But, leaving $ 3 for a 75 order???? It is an insult. 4 % tip.

I was a BJ dealer, and if someone tipped .50 or .25 (and hadn't tipped all night) I flicked that coin back at them.