More importantly the workforce is familiar with C/C++, how it’s listed on so many job listings. Which is kind of sad as a requirement. A programmer who can’t become productive with Ada after a few weeks (productive, not masterful) is not the kind of programmer anyone should be hiring for any job. The syntax is (almost) dead simple, for a reason.
Those jobs require competence from most contributors. Mastery from a few. And you can teach mastery to non-incompetent people, most of the time. Also, most jobs that Ada would be used for aren't time critical (in the sense of "Oh god oh god oh god we've got to ship yesterday!", unless it's F-35, which fortunately didn't use Ada because that would've saved them a lot of heartache). They program in 2-5 years for the project so 1 month to competency and then additional OJT from more experienced (with Ada and the system) over the rest of the time will produce mastery.