>>But real markets tend to be far from perfectly competitive. Depending on how hard it is to switch jobs, which is affected by factors like the level of demand by other employers for the same type of work, and the difficulty of retraining for other types of work, the employer may have a semi-monopsony status, in which case the wage may be far below the value the employer derives.
Of course real-world economies are highly chaotic/complex and are going to deviate from simple economic models, with numerous outliers that don't adhere to what would be seen in the assumptions of a perfectly efficient/competitive market that exists in economic model, but that is no justification for crude cookie cutter interventions that introduce systemtic distortions.
There is no reason to assume the distortions that exist in an ostensibly free market will generally push wages to below their market rate. They are just as likely to push it above. The most reasonable assumption that the distortions that push it above market wages balance the ones that push it below, resulting in average mostly aligning with the true market wage.
In the absence of definitive evidence either way, we should opt to trust basic economic theories and respect free market rules, and not actively intoduce laws that blatantly restrict contracting rights in the hope that these new distortions will counter-act some hypothesized imbalance of distortion that exists at labor's expense. These remediative rules are just as likely to exasperate existing distortions as they are to counter them, while introducing a host of new distortions that would otherwise not be present.
>>For that reason, unions and minimum wage laws, among other things, can often create higher wages without driving employers out of business (though not always).
The wage gains are not a free lunch. It comes at some cost. And that cost can include more than employers being driven out of business, though as we saw in the 50s through 70s in the US, that was often the outcome of unions getting a strangehold over major industries.
The fact is, it's impossible to measure the impact of every intervention in a large economy, whether it be rent control, minimum wage, or giving unions a monopoly over a company's negotiation and hiring decisions. In the absence of definitive evidence of the impact of any given proposed intervention, we should opt to trust economic theories that say price floors/caps create and obstructions of contracting rights create economic deadweight losses.