This is why they are a valuable part of an agreement. Including a non-compete means that your contract is lower risk for the employer, which can mean higher salary or better retention. Early termination terms exist for the same reason.

That said, a non-compete which prevents you entirely from practicing your craft would be a hard one to enforce, I've certainly never seen a contract like that.

If there are non-compete clauses in entry-level food service jobs, I hardly think they would bother to enforce them. The loss of a burger flipper from a McDonalds to a Burger King is less than the cost of lawyering them into a pit of despair.