Careful here ... non-compete clauses ARE enforceable if they are limited in scope. The idea behind them is to keep you from getting hired away to a competitor and then divulging what are considered trade secrets, like formulas, recipes, code, and other proprietary knowledge. Many an employee has gotten sued by a previous employer for doing just this very thing.

However, you are correct that an employer cannot keep you from working within your chosen profession. Those kinds of things are totally unenforceable.