No restaurant is being forced to engage with these delivery services. I would guess they either do it because it makes business sense (e.g. marketing)
I think it’s the free marketing — restaurants probably worry about their competition racing ahead. But it’s difficult to say many profitable walk-ins they would get as a result of being listed on Deliveroo and Uber Eats.
Secondly, there is no one forcing the drivers to work for these delivery services. I guess they either do it because they can’t get other work, it gives them some money, or they are just trying it out. Of course, some may just do it because everyone else is. If they can’t make a living doing the work, which it seems to be the case, then I guess they will go elsewhere (if they can).
Many drivers appear to use Deliveroo and Uber Eats as a way to supplement their income. There’s still really no excuse for paying such pitable wages though.