Several years ago, in my mid 40's, I was on the job hunt. I interviewed at several companies that seemed to love me and even flew me to the HQ for an interview (D.C., Utah, etc.) Most of the companies were the same; lots of young people sitting/standing at long tables in open offices. I didn't receive a single offer from any of them, with most of the replies being along the lines of "not a culture fit". I can't say for sure what that means but it sure sounds like ageism to me.

Interestingly, I landed my current gig with only phone interviews. I didn't even see my co-workers until 2 months after I was hired and we all met at a central location for a 2 day "summit".

I can easily imagine this happening. Makes me wonder what can society do about it?

Google for example takes hiring decision away from interviewer - the committee receives interview feedback in written form and makes a decision based on that, not seeing the candidate. You do lose a few bits of information that what, but it takes like half the bias off the table (the other half is allowing the interviewers to ask more difficult questions and being more nit picky in grading answers).