Do companies enforce every single time? No. Can they try to enforce, and win, if your manager is upset, dislikes you, or is just a bad manager? Yes. Do they ever enforce? Sure do[0]. Do you have any data about this or could you find any article indicating it's safe to not worry about non-competes (if they are enforceable in your state)? I looked, and I couldn't find any such thing.
Most times the employee is just going to give up, and pursue other opportunities that the employer can't or won't enforce a non-compete against. There isn't always going to be a lawsuit.
Have you gone over the detailed career trajectory of all these engineers you know? Do you think they would volunteer, without prompting, that they couldn't take XZY job due to a non-compete?
Even if you have had detailed conversations with, say, two dozen people, if big companies enforce on 5% of people, it's not unheard of that you personally might not know someone it happened to. That's especially true if you happen to live in CA, where non-competes are unenforceable.
[0]https://www.geekwire.com/2017/business-personal-amazon-web-s...