There's a survivor bias, you see the older techs that are employed and people think "oh, there's no problem." But people don't take into account all the other techs that could not continue their career because they could not get a job as they got older.
I don't think it makes sense to say they're the exception. I'm also mid-40s and have no issues finding employment. Most of my friends are mid 40s/50s and also have no issues. The vast majority of them have switched into management, though. Myself and the other older engineers I know are staff+, though, which helps a lot. I can't imagine being this age as a senior engineer trying to fight an army of equally qualified people in their 20s (who are also having issues finding employment right now).
They live in second tier cities and retire at the same time everyone else retires.
If you are 40 years old and still competing with 20 something’s based on your ability to reverse a b tree on the whiteboard, you have made some poor life choices.
I see these folks all of the time at client companies.
On the other hand, if you are 50 years old and haven’t kept up with tech - yeah you’re going to struggle