Are you talking about Uber/Lyft or completely unregistered/unorganized ones? I have been using uber in SF bay area. You missing one key point, there is an abundant number of drivers for Uber to choose from, and if the drivers/cars are even slightly unsatisfactory, Uber will drop them in a heartbeat and recruit someone else.
1) Their rating gets affected. Uber lays off anyone with less than a 4.5/5 rating. Uber also has a complaint service, you can use to report drivers. The local Yellow cab on the other hand always does this. I have never had an Uber driver take me the long route.
2) This a valid point. It is possible for Uber for take of care of this on the server side. I am not certain they do, but I hope they do.
3) Again, a valid point. I do agree, public transport vehicles should be held to higher standard than other vehicles. I am happy that the car are the cheapest cars, but I do hope Uber mandates regular maintenance. I also doubt they can be any worse than the yellow cabs we have here
4) This only works if the drivers are anonymous. It is absurd to think vetted drivers can get away with this.
5) Uber doesnt allow drivers to refuse rides. If they do, they are fired.