Tipping before a service is rendered is a silly expectation. It's really a bid for service through a middle man the way they have it set up now, and not actually a tip in the traditional sense.
I understand why they want to incrementally increase the cost as the customer proceeds, so they have already invested time in selecting items etc. If they charged a reasonable fee for the delivery instead of the "tip" and presented all the costs up front it would ward off a lot of business.
By the time everyone is paid a fair wage and the middle man gets their fee, that's a very large bill to wait an hour for some ultimately cold food thrown together poorly in styrofoam or plastic containers. Restaurants and takeout are already deteriorating in value proposition with increasing cost of labor and declining quality standards/portions since COVID. Best to cook everything yourself these days other than special occasions.