The FAA Academy where all flight controllers are trained is way over-subscribed. Recruiting policies aside, I can find no evidence that the FAA wasn't training as many controllers as it could through its academy. This fact remained true through the Trump 1 administration into the Biden admin, except for COVID. The pandemic was understandably a huge disruption, as were government shutdowns.
We can know this from the FAA Controller Staffing reports from 2019 (Trump 1 before the pandemic but after Obama) and 2024 (Biden). The 2024 report has been scrubbed from the FAA website when I last checked, but is available through the wayback machine:
2019: https://www.faa.gov/air_traffic/publications/controller_staf...
2024: https://web.archive.org/web/20241225184848/https://www.faa.g...
There appears to be no urgency in Trump 1 about this issue in the report. Things changed in 2023 when an external safety report revealed the staffing problem and suggested improvements.
https://www.faa.gov/NAS_safety_review_team_report.pdf
As a result, hiring almost doubled between 2010 and 2024, with 1800 controllers hired in the last year. More importantly, the FAA followed the report recommendation to use CTI schools as additional academies:
https://www.govexec.com/workforce/2024/10/amid-hiring-surge-...
It seems like the Biden administration took real action to address a problem that had been unfortunately present and unacknowledged for many years.
See a chatgpt analysis comparing the two reports here: https://chatgpt.com/share/679eb87f-c4fc-800a-a883-3b7f79e06d...