Every single one of these cases is someone who is too old applying to be an IC. That’s the elephant in the room no one is ever going to acknowledge but everyone knows.
If you're saying that's how it is in practice, because of shitty managerial practices and management lacking value for wisdom and skill of talented workers, sure. If you're saying that's how it should be because if you're an IC at 40 you're not good enough at what you do... no.
I started in this industry after military service, and at 40 I’ll only have a few years experience. Why would that be too old?