Tipping shouldn't exist, but that's how shit is setup in Assmerica. I end up feeling guilty if I don't give a decent (20-30%) tip, but I never use those generic services and only ever order delivery if the place provides the service themselves, and I still usually pick up my food myself even then. I can imagine how delivery people feel getting burned by lazy niggers all the time, so I would recommend just ordering takeout if you can. Even better, learn to cook for yourself. It's a lot cheaper.