The law can't actually do anything about discrimination as long as there is a slight professional veneer to cover it. Don't want to hire old people? Want to fire someone who doesn't like your ideas? There is a standard stock of phrases like 'cultural fit' which are unimpeachable in almost any context, and once hired, almost everyone is or can be construed to be in violation of some regulation. As long as you use the right words, don't let slip any stupid smoking-gun memos, there is nothing anyone can really do because it is impossible to prove anything.
The best protection is to be able to change jobs, and to stick with environments which do not contain toxic people who abuse their power or want to hurt you.
If you are older and a company does not hire you due to 'cultural fit' then you are probably dodging a bullet. Forcing them to hire you wouldn't make things better even if it were possible.