When they're marking the item price up, that claim is false. Given these apps' SEO juice and ubiquity, users are left with the false impression that Restaurant X sells a pretty expensive burger.
Like when you shop on Amazon - they say 'the TV is $x and our delivery fee is $y' - really the manufacturer charged them < $y but they mark up and then also charge a delivery fee, don't they?
Nobody looses their mind at this.
I would be upset if Amazon had brick-and-mortar stores and they sold me a $100 TV with a $10 delivery fee online, but that same product was available for pick-up at $90. I'd be fine with it sold in-store for $100.
We do flip out when these sorts of pricing tricks are used. One I can recall: Best Buy ran a bestbuy.com intranet in-store to wiggle out of online deals. https://www.engadget.com/2007-03-03-best-buys-secret-intrane...
Then they charge the customer for an additional service actually rendered - the delivery. They charge this as a delivery fee and a markup that they can vary on more expensive items. This is pretty normal for a retail business to do.