I worked at google for a few years.
I don't think google discriminates based on age.
The founders feel strongly that intelligence is more important than experience.
So they believe that they discriminate based on intelligence.
The problem I had working for google is that the company wants to employ only the "A" personality type engineer.
The "googly" engineer accepts no compromise, makes no mistakes and is driven to produce the best solution at any cost.
After 20+ years of working in the industry, I'm willing to compromise and to produce a great solution now until I can produce a better one tomorrow.
At google, the founders have stated that great is not good enough.
I'm an "AB" personality type and that "B" part is not good enough for google.
Google has amazing benefits and so working there is amazingly lucrative.
I would work there again if I could but I fear it would end the same.
At google, you need the approval of your peers.
The "A" personality types are the majority and as such they don't want any other types around.
(There are exceptions if you're charismatic or attractive but that is the same at other companies.)
The opposite of a correct statement is a false statement. But the opposite of a profound truth may well be another profound truth. -- Niels Bohr