So, we are assuming the pizza was $20. a 20% tip, which is still pretty standard, afaik, would be $4. WTF is this driver pissed about exactly?
Also, why the hell does anyone use these services? They take a huge commission from the restaurant, they don't pay their drivers living wage, shit is frequently wrong, or the driver is an ass. What benefit does this "service" actually offer because I can't see it.