When you buy food from a third-party delivery app, you have the option to tip. That money may (or may not) end up in the pockets of the delivery driver. No tip money ends up in the pockets of restaurant servers, even though they are very likely to be involved in putting together your delivery order in between serving tables.
I took a cab to the airport for a work trip recently and when I swiped my credit card to pay, the screen asked me if I wanted to tip 15, 20, or 25 percent. Sure, 25 percent sounds good, I thought.