Every job requires some amount of on the job training. FTEs of all levels at Google are practically useless for at least 6 months after they join, often requiring hours of training and 1-1s. It's pretty standard.
Yeah I agree that it sounds like a good deal until they fire you after two years and don't allow you to move up like they used to. These terminations are arbitrary, unnecessary, and legitimely harmful to people's lives, so no I don't think it's fair or humane.
I don't see why their initial skill level when they were first hired really matters here, people deserve to have job security based on current performance regardless of their initial conditions.
I don't see why I need to give up any of my salary for these people have job security. I'm sure a small portion of the funds allocated to stock buybacks should do. And, for the record, I already give 1% of my total comp to the union, which was created to protect people in situations like these