It is crazy the latter could land you on a blacklist. A rating system is not necessary. A reporting system for the rotten apples would suffice, and the rest of the customers would be unrated.

The guy brought to hospital may end up in coma. Not able to clean up.

With reporting you cannot have a pissed-off driver land a pregnant women on a blacklist because she delivered her child in the car, and there is now blood on the seats.

There is some occupational hazard for taxi drivers and others in public transport. The provider company or insurance should cover cleanup costs.