FWIW, Germany did build a maglev that runs up to 500 km/h, the "Transrapid" [1]. Development was started in 1969, and a test route was built in 1987. However, it was only ever deployed in production once, in 2002 - guess where? In Shanghai, connecting the Pudong airport to downtown (Correction: Not downtown, but to an interchange station connecting to a few metro lines.)
And hey presto, 20 years later China has a maglev. Honi soit qui mal y pense [2].
Yes, it is a pity. On the other hand, Germany is only around 1000 km north to south, and most distances can be done in a few hours with conventional high speed trains. And it doesn't look like there'll be export opportunities for a Transrapid anytime soon to, say, the US, or China...
If you limit yourself to Germany you are correct. However the EU is a thing, and could be made a lot better if the countries started acting together more. Maglev from Italy to Finland with stops in Germany for example.
The entire world is full of difficult terrine. Either you quit making excuses and learn to deal with it, or you make excuses and make flying easier. I visit Europe about once every 20 years, so I'm not really in position to say what Europe should do.
And hey presto, 20 years later China has a maglev. Honi soit qui mal y pense [2].
[1] https://en.wikipedia.org/wiki/Transrapid
[2] https://en.wikipedia.org/wiki/Honi_soit_qui_mal_y_pense