After a certain point in their careers, it really does feel like a large percentage of people stop asking "why?" when faced with new requirements, standards, etc.
Maybe it's just a natural part of getting older, as habits and perspectives become more ingrained over the course of time.
I'm not sure it's about getting older, but it does seem somehow related to age.
In my experience, the people who won't ask "why" aren't simply "older." They're the in-between. Young people ask "why." But also older people, maybe 50+.
My experience has been that it's the project managers and their overlords in the 25-49 range that seem to think they know everything and everyone else is unclued.
The young ask "why" because they're curious and want to learn. The old as "why" because they want to understand what's behind decisions. And managers hate explaining themselves.
Maybe it's just a natural part of getting older, as habits and perspectives become more ingrained over the course of time.