I am not a big fan of Deliveroo, Foodera, etc. either, but from what I've seen reported they are not too bad when it comes to treating their drivers (at least here in Berlin). The restaurants/kitchens also seem to profit from it and a lot of new places opened up specifically with those services in mind.

AFAIK your calculation also isn't true. Deliveroo pays it drivers 7.5€/__hour__ + 1€/delivery (or something like that), so as long as they do enough deliveries/hour, that should work out. I'm still more concerned about the absurd marketing battle, but in my personal perception it slowed down quite a lot the last months in Berlin.