This. Every "expensive" service can largely be traced back to the sheer cost of having someone on their feet all the time to perform it. 20% of my typical takeaway order price would require one complete delivery every ~30 mins to earn a living wage in my city - that sounds pretty reasonable.

Food delivery seems like the sort of thing that should be a set/tiered price. When I last used grocery delivery years ago that's how it worked.

It should probably be both, since the amount of space a deliveryperson has can be limited (especially those on bikes).