Understandable, but it's beside the point. The point is that legally mandated (and enforced!) employment agreements should exist regardless of the amount of people vying for jobs.

I mean in cases like that, unions often just constrain supply artificially. But that just creates a new problem, in that people who want to fill a role and are capable of filling a role can't necessarily fill a role that the company would be happy to give them if not for the union saying that this individual is locked out from filling the role.