Wind resistance is a problem at speed which is why production trains rarely go faster. Airplanes at altitude see much less win resistance. (hyperloop would also be good but will never be reasonable to build even if the engineering challenges are overcome)
Japanese bullet trains had to get a redesign due to something akin to sonic booms when leaving tunnels that annoyed the hell out of residents several times an hour.
Wind resistance is a problem at speed which is why production trains rarely go faster. Airplanes at altitude see much less win resistance. (hyperloop would also be good but will never be reasonable to build even if the engineering challenges are overcome)
Japanese bullet trains had to get a redesign due to something akin to sonic booms when leaving tunnels that annoyed the hell out of residents several times an hour.
Noise is another issue of course but energy is what will kill faster trains for forever