This. Rail is great for roughly linear population distributions (like Japan or California coast), but understand the USA had a huge 2D spread - laying out a vast rail grid is a lot harder than roughly a line. Each terminal had the same problem, as travelers are moving to/from in all directions. My own case: 2 miles to the nearest bus, then 20 miles to the subway, then 15 miles to what would be the high speed long range rail terminal - then a similar reverse sequence to reach the destination, at which point I'd have minimal luggage and no personal transport. Way easier to just throw everyone & everything into the family SUV and drive, taking a similar travel time with what I want and have a vehicle when we arrive.
Which is one reason why the Northeast Corridor works even though it's only sorta high-speed rail. There are a few cities off the coast like Pittsburgh that miss out but you handle a lot of population with a single line.
The only caveat is that, because it's not really high-speed, it works better as north and south segments than as one single line. But because it's NYC in the middle, even that works pretty well.
