[so33]

>What if people refuse to use the train because it's scary, dirty, stinky, etc.? What if you could re-imagine trains where everyone can bring their own private mini-car and add it to the train? Then the car can be private, clean, luxurious, cheap, or whatever the owner wants. Would people adopt it then?

Because the "private mini-car" isn't as space efficient as just having one person. Space efficiency is a major point of public transportation, and the "scary, dirty, stinky" aspects can and have been solved in other parts of the world like Europe and Asia. What public transport advocates are worried about, I think, is that just like freeways, we are potentially going to create an enormous strain on the surface road system... the cars are going to have to come out of the tunnels some time, after all, right?