Trains and buses don't really work unless your density is extremely high. Not everyone wants to go between the same small set of points along a linear route.

Trains and buses don't really work unless your density is extremely high. Not everyone wants to go between the same small set of points along a linear route. This is one reason why cars are much more efficient for many routes. Personal Rapid Transit offers the decentralized nature of cars, but eliminated many of its problems: having to stop at stoplights, the limitations of human drivers, etc. It can't handle huge masses of people the way a train can, but for suburban use it would really be a lot better than cars, and it would also be a much better option for higher-paying passengers than traditional cabs or Uber/Lyft.