They used to give aptitude tests before the USSC declared the tests discriminatory (Griggs vs Duke Power). So the alternative was to require something that would show ability. Voila! Require a college degree in the area of work.
I had to take the Federal Government Entrance Exam after I graduated. I scored 98.8. My wife who had graduated at the same time had been given an automatic grade of 100 because of her 3.97 GPA.
She took the FGEE just to see how she would do. She scored 89. I was tickled because my GPA was a lowly 2.2. I think it did surprise her that I beat her so bad. She was named outstanding business student at Oklahoma State and on the Deans list every semester.