Let's drive down wages first with lots of visas and companies colluding to not recruit amongst themselves.

Unfortunately, there aren't. Or, rather, there are, but not easy to find and not so many. Not enough for the amount of work that is out there.

Bullshit. If you are turning down people for "culture fit" or perceived ramp-up time, there is no shortage.

You are assuming "culture fit" is just an excuse to interview somebody, waste all that valuable time on evaluating them and then reject them under a transparent ruse. Why would a company do that, where's a upside in that? Culture fit is a real thing and if the person does not fit the team, it would be an expensive mistake to hire that person. Shortage of talent does not mean the company would hire anybody. It just means it is hard to find people that they want to hire. There could be plenty of people that they don't want to hire, still.