Aside from the "sharing economy"'s brightest lights being designed to enrich everybody but the people doing the work, while offloading all of the risk onto the people doing the work?
Nothing, I guess.
Nothing, I guess.
Same with AirBnb.
If they're not making money - why would they be doing it?
Theres a reason most of these industries have existed unregulated through out history, exploitation occurs, become regulated, and are now reappearing with a new tact and hitting up existing laws... and hence all the court cases where they are desperately trying to claim the services aren't illegal.
Theres a lot of consumer safety to be considered you rarely hear of, let alone what is technically stealing by reselling things you don't own. Theres a reason regulation happens, and its usually because exploitation occurs.