I think it's just the degree. Instead of saying we charge 10% on gross plus a delivery fee of $x based on demand, they add margin to everything and double charg

I think it's just the degree. Instead of saying we charge 10% on gross plus a delivery fee of $x based on demand, they add margin to everything and double charge (service fee vs tip) for things people are unsure about. On the other hand, it is indeed a luxury service and people are free not to use it. The market will correct it if it needs correcting. In the UK, this would never fly as pretty much every supermarket has home delivery with identical online v in store pricing + delivery fee. It's much more honest.