If you look at the Ruby Bridges pictures you'll see school aged kids who are still very much alive and vote like crazy. I pointed this out to my brother one day and he was totally caught off guard. And he's a pretty smart dude, it's just something that has been framed as "in the past" to us our whole lives by pretty much every institution. Propaganda works, very insidiously.

Most of them were probably just quiet racist beliefs at home and in implicit ways in public.

It's easier to miss, but it's also easier to retreat from, since it's not such a public belief.

Just like most people weren't civil rights activists, most also weren't frothing rally style racists.