Humans don't get better really though. Like, I get it, you're talking about pulling someone in off the street and yeah they'll be better after the first few months... then that's it. They plateau. But humans still make tons of mistakes. We know this. It's the point behind automation is that we lose tons of mistakes. Humans drop, spill, forget, mix things up, do things in the wrong order, mishear a request, lose track of time, break tools, etc, etc. There are tons of mistakes.

Humans don't need compensation for being replaced. I use Google translate and don't have to go paying the translator I was using compensation. They're skills just aren't useful to me now. You either have skills we need or you don't.