Is it required that the actual job pay adhere to the salary range posted, and no different? How about if companies pay more than the range quoted, so that the

Is it required that the actual job pay adhere to the salary range posted, and no different? How about if companies pay more than the range quoted, so that they simply post low salaries and negotiate up? If it's not required, then how is it an improvement on the situation that everyone is still basically negotiating what he/she can justify? Also, what does it do about the situation when a job's compensation is largely not salary but stock?