For all but some very egregious cases this will not be enforced. AWS lost a bunch of VP-level execs and they went to work at Microsoft... If they didn't use it against them they won't use it against anyone.
I agree, but it's still problematic. A couple concerns off the top of my head:
1. This can impact behavior of the labor force despite lack of enforcement. Not everyone can afford to pay a lawyer to review their employment contract, and not everyone will have the knowledge to know if such terms are applicable or enforceable to their situation. This causes fear and hesitancy which in turn drives behavior and decision making.
2. If you're unfortunate enough, there's nothing stopping a company from attempting to make an example out of you. Even knowing it's unlikely a former employer will come after you, why should individuals be forced to take on that risk to earn a living?
