They were invented decades ago.
They have fewer moving parts than wheelbois.
They require less maintenance.
There’s obviously some bottleneck in expanding maglev technology, but what is it?
fwiw LN superconductors that operate at much higher temperatures are already being built https://eandt.theiet.org/content/articles/2021/01/superconducting-maglev-train-unveiled-in-china/
Also, China manages to charge only $8/ticket for the shanghai maglev, so evidently it can be done cost effectively.
If you subsidize anything enough it can be cheap for people to buy. That doesnt mean that its actually cheap to build and maintain. And the reason why temperatures are kept far below the critical temperature is due to the critical magnetic field and critical current decreasing as temperature increases even below the critical temperature
