As a user there is a strong pull not to tip after paying the premium for the initial service. For example an order for a $10 burger costs $20 and is delivered cold, I don't really want to tip for that. But then the driver shows up and its some down on his luck father lugging his son around because he can't afford child care, of course I'm going to tip every driver I see from then on (and feel ashamed for using the service in the first place).

Either consumer tolerance for convenience spending is going to break, or the prices will just keep going up astronomically as a perverse form of inflation (indirectly suppressing all jobs who's compensation isn't similarly skyrocketing).