Unfortunately this type of training is like advertising- a good chunk of the money spent on it is wasted, but they can never figure out where or how large the percentage is (or needs to be). But we still have, and even live by, advertising.

You can't say it never worked even once for a trainee. It probably works with some of them. But for some it also kills productivity and incentivizes job flight when your trainees could be working productively and enjoying their jobs.

It's a bit like the death penalty- say for the sake of argument that having a death penalty on the books, in locale X, deters 10% of all murders there. Is 10% enough to call it a deterrent or not?

In terms of my personal experience, I learned some things in the compulsory sessions I've had to attend in various workplaces, but I don't suspect I'd ever have been a problem to my employers without them. A few people I've sat next to in this training still "offended" even after attending (or signing in then leaving) the courses.

In the end, I suspect it's mostly a cost-saving CYA measure, which mitigates damages when the company is inevitably taken to court ("You mean to say, Ms. HR director, that you never created a mandatory training program, not even a handbook?" "This is why, ladies and gentlemen of the jury, my client deserves 3x $50M instead of $50M, for the horrors he/she had to endure working at company X")