Instead of mandating the standard to be used, they should've mandated that phone vendors agree on one standard, with a revision every x years or so.

Luckily, that is exactly what happened! The law explicitly states that it will be reviewed every few years to determine whether USB-C is still the best choice.

And why would a better choice magically appear though when it’s illegal to put it on the market to let it prove itself? Why would anybody who is actually innovative pay to research and risk such a better choice in the first place? To wait for its review in a few years?!

Sounds like you describe how aviation and other critical tech work. Every single piece has to be checked and validated by the administration, and yet planes keep flying.

This is indeed what literally happens in tons of sectors where standards are adopted or mandated by law.

It's insane how entitled tech companies are. They see perfectly normal and useful for the consumer standardization as oppression.

The ideal is two or maybe even three standards. Having one means that upgrading to any new standard would never actually be possible.