Why is ageism socially acceptable?

[Lord Halifax]

Why do so many young people consider ageism more acceptable than racism, sexism and homophobia? Like skin color, biological sex, gender identity and sexuality age is also an inherent quality you can't change and isn't responsible for, but it seems to be perfectly okay for even the most woke types to use people's age against them, use ageist slurs and dismiss other people's opinions because of their age.