Is not some regulation necessary? Spectrum is limited. You seem to have thought a lot about this so curious about your perspective.

Spectrum used to be a lot more limited when frequencies had to be exclusive and baked into hardware designs. Now we have agile radios that can tx/rx across wide bands and dodge other peoples' traffic, so the motivation for exclusivity is a lot weaker. If you walk around with a spectrum analyzer you will see traffic voting with its feet and overwhelmingly choosing the free-for-all ISM bands because dodging other peoples' packets is easy compared to obtaining spectrum licenses around the world.

So: the optimal regulatory approach changed, the laws didn't keep up, and now we have suboptimal regulation that isn't bad enough to spur a fix and vested interests (spectrum owners) who don't want it fixed so I expect it to continue for a very long time. So it goes. It's not great but if all the world's problems were as small as this one it would be a much nicer place.

My spark gap transmitter doesn't care about your spectrum. Regulation is important.