I've tried a few times (whenever somebody sent that sort of gift card my way), and it was always >$10 in explicit fees, plus all the menu items being silently marked up 20%.
Mind you, that's still not exactly "expensive" for delivery [0], but I can make better food both faster and cheaper than waiting, I can pick it up and actually use an insulated bag faster than waiting for delivery, and pretty much any other food strategy at least guarantees I'll actually have the expected meal and not have to waste my time with customer support (or money if I decide it's not worth the hassle).
[0] Imagine you're a driver, you incur $3 in actual expenses, the delivery takes 15min, and they have to wait 15min for the food to be ready (this is the thing that makes pizza delivery more efficient -- as soon as you get to the store there's another pizza waiting). Suddenly that's a $14/hr gig without any benefits and where you need to purchase a special insurance on top of things, assuming the only part Uber keeps is the 20% fee they're scamming you out of. Beyond that, you're at a much higher risk of bodily harm than doing something like construction, and if those aren't good drivers I don't really want to be encouraging more of them to be on the street, especially with time pressures (and if they are skilled ... that's less than McDonald's pays even before you factor in benefits).