But there are reasonable restrictions for lower-pay workers too. E.g. requiring that your secretary not work at your direct competitors for two years after leaving. Secretarial jobs at your competitors are probably a tiny fraction of the whole market for those jobs.
Replying here because I'm rate-limited: Because your secretary might know a great deal about your business strategy and plans.
Peon (aka almost everyone reading HN) non-competes almost never include any kind of compensation. Companies rarely pay above-market rates or offer to pay anything during the non-compete period. They basically slip it into the employment agreement because they can.
What's good for the goose is good for the gander, don't you think? In the legal world it's called "consideration", as in courts often invalidate contractual provisions or whole contracts unless there is some kind of consideration, and especially when the balance of power is tilted.
The only acceptable non-compete is where they pay you to not work for a competitor.
This is how it works in banking
If your scenario were what companies by in large used non competes for then I doubt anyone would have a problem. But in the meantime they're mostly using it to fuck people over en mass. Maybe if they behaved like adults, but in the modern business environment where anything legal is good, sometimes you need to take away the toys from entities that basically act like a bunch of toddlers.