If Apple was up front and said to each employee that they could not work for Google for 2 years after leaving that would be okay. Since it would be up to the employee to agree to those stipulations. Instead Apple took away those employee rights without telling them.
Non-compete agreements are unenforceable in California under most circumstances, as well as several other states. As I pointed out they can't legally take company IP with them. If they are actually sought after for their talents, they wouldn't need to do so anyway. What Apple and any other company can reasonably expect of their departing employees is that those employees do not take trade secrets with them. It's not reasonable for a company to restrict the employment of anyone once that person is no longer paid by the aforementioned company.
Edit: I'll add an example here.
Beyond that I don't think you understand the original purpose of non-compete clauses, because what you describe is always a gross misuse. Industries that rely on services and client relationships like them for the purpose of preventing someone such as a lawyer at a given firm or an art director at an ad agency from taking clients with them upon departure.