Surely most employers use IQ which varying degrees of effectiveness?
I expect in most settings IQ 100-140 is very hard to guess from an interaction. Harder if there is a specific field being assessed where someone has experience/training.
But everyone will pick up IQ <90 almost immediately and that's not even necessarily abnormally low just borderline.
De facto they are, mostly[1]. The corollary that there exist jobs where intelligence isn't pertinent is perhaps somewhat baffling to common sense, but then the law often is.
Huge tech companies have used the Wonderlic IQ test as recently as the last 10 years. Somebody here, if this thread isn't moribund, can chime in to say which; I'm not saying. There's a meme that IQ tests are a powerful hiring tool that have been suppressed by political correctness or gunshy HR departments, but the real reason they're not ubiquitous is that they're not fit for purpose.
I expect in most settings IQ 100-140 is very hard to guess from an interaction. Harder if there is a specific field being assessed where someone has experience/training.
But everyone will pick up IQ <90 almost immediately and that's not even necessarily abnormally low just borderline.