But the thing is that electrified rail networks doesn't address the quadratically increasing losses from drag at high speeds. There's a reason you don't see railroads operating at airline speeds: drag at sea level is a killer. In fact, at high enough speeds, the energy of air travel is actually LOWER than that of a sea level train.\
Altitude gives you a lot of efficiency. The idea of the vacuum train is to bring that efficiency down to sea level. And I think it's a good idea, but a real engineering challenge. In principle, you can keep a vacuum pretty easily. Vacuum tubes remain sealed and evacuated for decades without energy consumption, for instance.
It's just at the interfaces you have to worry about leakage, and there it's a matter of careful sealing. It's possible to get really good at it. The International Space Station is full of interfaces (and thermal cycling every 90 minutes) and would quickly run out of air if we didn't know how to maintain a vacuum well at interfaces.