EDIT: The fact that these crimes "have happened at hotels/in taxis as well" ignores the fact that they are far more likely in an environment where regulations meant to prevent or reduce them are wholesale ignored.
If I'm a fisherman in Florida, and I need to follow regulations for the fishing industry there, they don't have a stipulation that you can't discriminate against certain persons based on age, raced, gender, etc. when you take customers out on expeditions.
Why? Because that's covered by United States law.
Yes these things happened, and yes they are atrocious but they have nothing to do with the regulatory gray areas that these companies operated in.
With a centralized platform, people selling rides or lodging actually get recorded when they reject people, which makes it possible to pursue them for discrimination.
- Uber/AirBnB's regulatory abitrage
- assault, harassment, or illegal discrimination
but this is a complete non-sequitur. The laws that they're avoiding have nothing to do with individuals hurting other individuals. And assault, harassment, or illegal discrimination are perfectly possible in the context of a licensed hotel or taxi.