Do they?
Huh? Where did you hear that?
The reality is that Asians score the highest on IQ tests, whites score somewhat below, blacks score lowest.
The accepted wisdom is that Asians have the highest IQs, followed by whites, followed by blacks.
Well, that's not entirely true. Ashkenazi Jews have the highest IQs, but their IQ-advantage is in the verbal area, which is why when you see lists of the highest-paid lawyers a disproportionate number are Tribe members.
Keep in mind that these are averages. There are plenty of dumb Asians and there are plenty of smart blacks! You can't apply group statistics to individuals.
I definitely got these in tech interviews. Thoughtworks gave me one last year.