Also no material non-public information even if it's not technically technical.

The standard I'm familiar with is, knowledge you acquired during your time at a previous employer is safe to share with your current one if you can support it with a citation.

> Even in California, you can get sued for violating an NDA when going to competitor if you bring private technical data, which seems like a reasonable compromise. You can bring your expertise, but no code. Intersecting with this are patents. A company can also protect its IP with patents, but when should choose to disallow, or have more liberal patent laws? It seems there are similar tradeoff between the value to companies, competitors and public interests.

What does that have to do with non-competes? What you're describing is IP law and theft; and is illegal pretty much throughout the western world.

Non-competes specifically and only exist in the context of barring employee competition and migration of talent. All via legal labor servitude at the justification of "training investment" and/or "unfair competition".