The demand for such labor isn't strong enough to require living wages in relation to the supply available to obtain the desired number of workers, hence why people call for government action.
Employment ALWAYS requires living wages with exceptions happening on the side of the employee's needs (for instance, only needing limited total salary as a student for supplementary income). That's the cost of doing business. If you cannot pay that, you do not have any business running a business. But if we're going to apply your logic, then executive salaries should all be taking a massive cut. There certainly is no shortage of people who could or would want to be executives in the current market, and metrics generally do not exists to quantify which, of all available candidates actually are the superlative candidates. The reason it doesn't happen is there is a gross disparity in the negotiation power between executive level positions and the lowest paid positions within a company's hierarchy.