A company is its staff

Yes, but company policy and interview decisions don't necessarily match.

That quickly turned metaphysical. If company policy is neither enforced nor followed, is it really company policy? If so, "company policy" is just an abstract term that doesn't necessarily reflect the company in any way.

It really boils down to what I've already said. A company is its staff. What its staff does and accepts other staff doing is ultimately its policy. Anything else that they might have written down into a document that isn't enforced or followed is not company policy, but a way to compartmentalize responsibility and blame once its actual policies come under scrutiny

I didn't mean to get metaphysical. In my experience interviewing for software dev jobs, the interviews are usually conducted by the IT/software dev staff and the hiring manager, not the entire company staff. HR may or may not get involved, but usually they aren't making a hiring decision. The company may gladly hire a 50-something manager, or accountant, but the group of developers interviewing someone my age will have a bias against an older programmer, regardless of policy or whom they might agree to hire in some other role.

The company (and the law) have rules about discrimination and fairness, but when a group of 20-somethings interviews an older programmer those rules may not matter. Fixing age discrimination probably shouldn't focus on laws and company policies, no company has a policy condoning age discrimination that we need to fix. It's the software dev culture that equates age and experience with "not a good fit," for whatever reason. I have my own theories what those reasons amount to but regardless of why I think it happens, it clearly does.