They gave us something similar to an IQ test - some logic, some reasoning, some general knowledge.

Afterwards a guy called me into his office. Said nobody had ever aced this test before, and joked that I should be applying for his job. Told me bluntly they weren't going to hire me, because there's no way I'd stick around long. Guess he would have been right...

I've much preferred the "boring" jobs I've had to the brainy ones, which I mostly find to be miserable. I'm only not doing a "boring" job to this day, because they don't pay half as well as the brainy jobs. Not sure if that's a majority attitude among my peers (or those smarter than me, of whom there are plenty) but given all the other personnel problems low-skill employers put up with, I can't imagine smart-person-boredom would even register.

Now, smart people deciding they'd prefer to like work less, but have way more money? Or deciding at a much lower threshold that they don't need to put up with abuse or even illegal behavior (so very, very common) from a manager, and leaving, since they have tons of other options? Those, maybe, would tip the scales. I'm skeptical that boredom is the main problem, though it may be a nicer (to the employer) way to put it.