From what I've read last week [0], the main problem is that there's not enough (qualified) candidates being hired, and current ATC employees are routinely working 6d x 10h weeks.
Stressed & overworked employees doesn't seem like a great solution to critical life/death situation either.
“I found the
diversity in hiring air traffic controllers increased after the termination of the AT-CTI. However
applicants in underrepresented groups are more likely to be lost through attrition in the FAA
Academy Air Traffic Controller Training Program.”
We make a big deal out of interview process in Software engineering. But when it comes to critical life/death situation jobs, we don't.