@me_little_me why the angry reaction?
Because I think your statements are out of the ballpark.
I don't know if you have been renting cars lately on your own dime, but rental car companies have become worse and worse in the last few years (Covid aside). Service, costs, ripoff add-ons, misleading pricing, attitude and reliability IMHO have been going downhill. It was a bit different when my company paid for the car rental. I could tell the rental company they could discuss it with our corporate attorneys, could simply tell them to keep their car and rent from another company (my company always backed me on this) and file a complaint with my company (which got a communication from them as we were a big customer).
My car moved 800 miles by train is much better than renting a car when the costs are right or the decision is the best overall. I have a fuel efficient car that I know the condition of; don't have to fight third party companies trying to blame me for problems; a reliable, trustworthy insurance company; my own vehicle where I can go or not go at will; familiarity with the vehicle; ability to have emergency tools I want; car safety options I want; no extras required; etc, etc.
How using a rental car rather than my own car in an area where a car is required causes urban sprawl is seemingly in outer space. Urban sprawl is related to living in one place and commuting to work or driving to stores, fitness centers, etc. not to visiting places with little or no usable public transportation and places of interest.
As to cost, Amtrak needs to decide if multiple trains pulling vehicles is practical, how to implement it if possible and have an open mind on alternatives. They do not have an open mind on anything IMHO, have more interest in cutting costs than adding revenue, don't like working with third parties, don't like giving out any information to their customers (passengers, cities and states that hire them to run trains) or their owners (the American people and the government represented by congress) and don't like partners (witness their poor treatment of Private Varnish).
I thought my "comment" was sufficient. You asked.