Non-competes generally require consideration, time limit, and geographic range to be enforceable. Again rules vary by state.
In 40 years working as a programmer in multiple states I can’t recall signing a non-compete more than a couple of times. Obviously lots of people with non-competes change jobs all the time, so I don’t think it’s a big problem unless you actively harm your former employer.
> I don’t think it’s a big problem unless you actively harm your former employer.
Anecdotally, I've heard of two situations where employees left a business to start their own business directly competing with former employer, in both cases the former employer initiated legal action. In both cases they ended up with viable businesses after a year or two of legal battles. So if you're thinking of doing this, might be worth getting legal advice first.
If you're given a new contract to sign with non competes etc you can always try striking out the clauses you don't like then see what the other party does. This probably isn't a winning move if you really need the work but if you have other options and can afford to walk away it gives you a bit more flexibility to ask for better terms, many things are often negotiable.
That said, if you were the lead designer at a company and held multiple patents, and another company offered a lot of money because they wanted to steal the secrets ... well that would go to court.