> but it happens to other professions like personal trainers
Funny enough, this exact issue caused me to lose a personal trainer.
See, he opened a gym that competed with the gym he trained me at. Like, he was the owner and manager of that other gym. While also being an employed personal trainer at my gym. And did not hide this fact from anyone.
When the gym told him he had to quit or be fired, even he was of the "I'm surprised it took this long" perspective and understood their reasoning.
Line cook is an extreme example but it happens to other professions like personal trainers. There has been cases where non competes were forced on restaurant workers.