the non-compete was restricted to the area he was working in; he was told he would be working on kindle. It was not until he was hired that it was disclosed he was working in this much broader area of tablets (aka the kindle fire). Amazon presented it as a very narrow non-compete in the e-ink reader space before he was hired.

So he essentially signed a blank check.

I'd bet the others had similar non-competes. However, Amazon is becoming notorious for trying to enforce them.

Given that those offers were in California, they probably didn't. Excepting certain rare circumstances, non-competes are unenforceable here.

And thank goodness. One of the reasons the tech industry in California is booming is the large talent pool available to employers.

A company can sue you in, e.g., WA state court, and get a judgment based on WA law, that is enforceable in CA.

If you are subject to a noncompete & moving to a state where they aren't enforced, the smart thing to do is to get a summary judgment in that state. Otherwise jurisdiction is a matter of who shoots first.

Sure. Sorry if it wasn't clear, but we were talking about offers from Silicon Valley companies for jobs in California. Even if they put a non-compete into the contract, it is unenforceable.