For example one can hold capital, workers cannot just hold labor (workers need wages to survive), also labor value changes all the time with productivity changes, at the same time as productivity goes up price does not necessarily go up, since the demand for work is stable its just equal to the working population, while the demand for labor may change based on aggrigate demand. The holder of capital will always pay the least while getting the most out of labor, also a difference is that labor is a PRODUCER of value, without any innate use value, its use is producing other use values, as such it would be priced differently from commodities whose value is its own use value.
Demand for labor however is not necessarily based on the price, its based on aggrigate demand in the economy, i.e. how much profit is able to be made. So for example if labor price goes up, supply is the same, yet aggrigate demand for goods and services is steady and profit is still being made the demand for labor will be steady.
Not to mention that a ton of aggrigate demand COMES from wages, putting a whole new spin on it.