"A diesel train doesn't take you door to door"
Trains can go from city center to city center, or from one part of the city to another, notably quite a bit faster than the car. then, one can walk to their desired nearby destination. Humans are capable of walking.
"and diesel is more polluting than gas"
true, but the quantity of gas-powered cars in the united states is greater than the quantity of diesel trains, and trains can be powered by electricity.
"I don't like cities."
that's not the rest of america's problem.
"Cars are not the problem."
Cars themselves aren't the problem. However, over-dependance on the car is.
"Generation of electricity is the greatest contributor to climate change."
True. However, abundance of car use adds to the fact.