Every PI wants only the most brilliant, creative and motivated trainees that will put in insane levels of effort to advance the lab agenda.
We know this because it is how they write their postdoc solicitation blurbs.
This is not what is consistently available.
I know this because a consistent backchannel theme of my dubious life online as science careers nerd features PIs complaining about their trainees.
My usual response is to point out that they became PI due to being much better than average. So of course most of their trainees aren't going to be as good as they are*.