That would be true if US passenger rail was actually capable of high speeds to start with.
As it stands right now US passenger rail is total joke compared to the rest of the developed world. Slower, less reliable, more expensive. Air resistance in the US is the same as everywhere else, so that isn’t the limit factor.
That is just one of the limits. At the speeds hyperloop was proposed to go, you need really wide curves to limit g-forces on the passengers. Not just when going left or right, but also up and down. It would be an absolute nightmare to get all the right-of-way done, and even then you would need immense amounts of earthworks to start curving uphill miles before the hill actually starts.
I agree. Lets stop trying to innovate trains. The laws of physics make it clear there isn't much left to do for speed. Any innovation left would be around construction (and even there the world is doing well, most innovation really needs mass production)
The limitations are financial (both building the tracks and acquiring at some new right of ways) and geographical (a lot of distances in the US are quite big and most people won't take a train if it's a lot slower than flying).
None of the reasons that the current passenger rail system in the US is horrendous are technical. It's entirely feasible to build proper passenger rail networks with current, look at Japan and western Europe for some examples. The problems are all sociological in nature.
You can plasma sheaf the train head. The stability of wheels/rails and other mechanical stuff at say 700km/hour is probably a bigger issue than air resistance.
Nobody has tested maglev at 700km/h. https://en.wikipedia.org/wiki/Railway_speed_record The conventional train speed record is only 30km/h slower than maglev. The issue with the conventional train wasn't wheels it was the overhead wire contact (though at that speed maglev is more efficient)
