Why we ever thought going backwards was a good idea I'll never know.
We started with rail. It was great. It allowed us to expand across the country. We could move long distances quicker than ever.
We improved on that idea with the car. Not only could we go long distances relatively quickly, we had the freedom to move around once we got where we were going.
We improved on the car with the Airplane. I doesn't have to take 25 hours to get from NH to FL anymore because we can fly there. I can still use the auto (rental) when I get there for local travel, so I don't have to walk 5 miles to get groceries.
Why are we moving backwards to the train again?
We're not. The train represents forward thinking.
When "We improved on that idea with the car" should people have complained that we were moving backward, because roads were a very old creation which existed back in roman times? Should the automobile have similarly been abandoned because it relied upon wheels, which was an even older technology?
Trains of the 19th century and those of today have about as much in common as does the automobile and the horse & buggy.
Would it be impossible to create a rail system that travelled high speed that you could pull your car onto?
Such a system was created - in 1971.
You could save on gas, stop worrying about traffic, hop in the back seat and watch a movie with the kids.
Yes, Auto-Train passengers do so every day. The single existing route should be expanded and gradually improved to produce higher speeds (and thus faster running time) and greater capacity, but that costs money which Congress has never made available (they only relunctantly funded replacements for fifty year old rail cars). As discussed in this thread, billions are being made available (mostly wasted) to conduct studies of expensive "high-speed" rail systems which will never be built, but nothing to fund the relatively modest cost for expanded and improved conventional rail (which is the greater need across most of the nation).
Could you build trains that would connect and split real time based on the travellers destination, so they don't have to stop at every station?
Yes, real railroads have only been splitting and combining trains enroute since, oh, maybe a hundred years ago. The upcoming Jacksonville to Miami train that Florida is still proceeding with will likely do this.
I have lived in Japan and I have lived in Europe. You are talking much smaller counties where rail works. Due to the size of the US high speed travel between cities will always be by plane
The idea that passenger rail won't work in the U.S. due to geography (primarily greater distances) is a myth. While the United States is a larger country, most people aren't going all the way from one end to the other, or even close; Most current rail trips are less than 300-400 miles, even when the train itself is going 2,000 miles.