It’s easier to quantify differences between candidates with aptitude tests than anything else, and I suspect that’s the reason the tests are carried out in addition to the simulator assessments. If there were only x available jobs and x + 30 candidates met the minimum requirements in everything, how would you objectively determine who was going to make it and who wasn’t? Using the scores obtained in the aptitude tests is a reliable way of making the decision; even if what they are measuring is not raw piloting ability or necessarily any use whatsoever on the job.