You must be younger than 31 to qualify for training as an ATC: https://www.faa.gov/faq/what-are-age-requirements-individual...

Does seem odd to me - why restrict it this low? People are living longer and healthier than ever into older years (and better vision)

The job requires 20/20 uncorrected vision near and far. After 50, that starts to become pretty darn rare. The mental load required to keep all of these moving parts in your head and recall both what you have instructed them to do and what needs to still be instructed in the very near future requires a mental acuity that is not a young person's game. It can also take years for an ATC to have the experience required to meet the most pressing needs. I can see why they don't want to waste their efforts on people likely to be unqualified soon after reaching a useful level of experience.

> The job requires 20/20 uncorrected vision near and far.

Isn't it 20/20 corrected vision?

There is a maximum age for atc applicants (31) that unfortunately makes this infeasible.

A lot of pilots seem to retire into commercial aviation after their military careers. They already have all the training and flight hours. After 20 years and a pension they're keen to keep on flying, but not as high-speed.