AM Radio has an extremely important role in emergency broadcasting, because you can cover a whole continent using just 3-4 broadcasting stations, and it is so easy to demodulate, that you can build completely analog recievers that need no power source (they use the carrier wave as a power source). This also means that AM receivers are very cheap, so in a lot of developing countries the only broadcasts most people can afford, and will reach them are AM.

I think we should keep AM radio around, at least for emergencies.

Also, unfortunately, when HF bandwidth gets freed up, it mostly ends up going to companies that use it for high frequency trading, and not to things where it would benefit the public, like ham radio, or digital broadcasts.

As someone who has minute knowledge of how radio works, what could those frequencies be reclaimed for?

No.

Enough analog broadcast spectrum has been destroyed for almost nothing.

I still can hardly believe they wiped out broadcast tv signals for . . . What did they do it for again?

My understanding is that the EU -- higher density, more languages (so more radio stations that nearby people can't use), more-congested radio spectrum -- has done this, forced a switch to digital car radios, and has generally placed more weight on ways to acquire more usable bandwidth.

The US, without the same level of pressure for the frequency spectrum, has placed a higher priority on not breaking compatibility, keeping existing devices continuing to function.

https://en.wikipedia.org/wiki/Digital_Audio_Broadcasting

In the European Union, "the European Electronic Communications Code (EECC) entered into force on 20 December 2018, with transposition into national legislation by Member States required by 21 December 2020. The Directive applies to all EU member states regardless of the status of DAB+ in each country. This means that since the end of 2020, across all EU countries, all radios in new cars must be capable of receiving and reproducing digital terrestrial radio."