Yeah. Trial employment better be paid! :) Even with pay, unfortunately, folks with an existing job often can't take the time off. And when people have the option between one company making an offer and another with a trial period, they often go for the offer (which makes sense). The other issue is that a company can't do a trial period with every person who applies (too much cost for the team), so there has to be screening step in front, which sort of just moves the problem to an earlier level.

I do think trial employment can be a great thing. But it's not a universal replacement.

Trial employment immediately screens out candidates who do not have the time or patience to spend an entire day working very hard with a prospect. It also introduces an NDA, a need for a sandbox, etc.