The driver seems to get shafted in all cases in this industry and for the likes of Uber taxis etc, but having looked into this the restaurant trade are quite unhappy with the power the delivery companies have gained, such that, despite supposed competition, they're all effectively acting like a cartel.
What's more, while they can take as little as 15%, they want to then have some exclusivity and even expect to be paid more so they can do the marketing, which a smaller restaurant might see as valuable, but must now increase its prices for. As the cost of living goes up, I'm sure less and less people will pay the higher prices for what is often relatively simple takeaway food (that isn't mean disrespectfully, but rather there used to be a difference between a takeaway shop and a 'proper' restaurant).
McDonald's adds a sizeable markup (despite an exclusive deal with Uber Eats), but some other big chains take the hit, presumably so as not to lose trade or create badwill.
It seems like a minefield and perhaps this wouldn't have happened without Covid, where restaurants became so reliant on home deliveries that they allowed ever worsening terms and conditions.
Suffice to say, I vote with my wallet and don't order from McDonald's or others that grossly overinflate their prices.
