DoorDash has a warning for customers: If you don't tip, prepare to wait. A pop-up was added to the delivery service app this week if you enter a zero in the tip amount. It warns customers that orders ...

It used to be that we had to at least talk into a phone — and at one point, that phone was plugged into our walls — if we wanted food delivered. These days, apps like DoorDash, Uber Eats and GrubHub ...