Seattle has had a remarkably good experience so far. The current service from dock-less companies is not only better than Pronto (municipal bike share) was, it’s already better than Pronto could have ever been.
Regarding “it’s the city that does have to worry” about damaged bikes being left on the streets, Seattle’s permitting addresses that well: https://www.seattle.gov/transportation/bikeshare.htm (click “Bike Share Permit Requirements”)
VC funded business not having to worry about the losses when bikes are dumped or trashed... it's the city that does have to worry.