Even if you have fenced in and dedicated roads, there are system control problems that will always arise. The more vehicles the greater the opportunity for fail

Even if you have fenced in and dedicated roads, there are system control problems that will always arise. The more vehicles the greater the opportunity for failure of the system. Even today, simple systems like automated industrial plants have to have humans monitoring them closely to ensure that any errors that arise are actually handled properly. Once you put a large number of vehicles in play, the entire dynamics of the system would become unmanageable. You would require multiple hot redundancies at every level with human monitoring to at least minimise the things that could go wrong. It would only take one coding error for the entire system to fail and that coding error might only ever be found after some disaster has occurred. It might be nice to have self-driving vehicles but the cost may be so prohibitive to make it infeasible.