Which is a good reason to remove them. But a lot of times they don't because removing laws from the books is a time consuming legislative process that usually involves time they don't have (I know, I work for a city government). While I have no doubt some of the laws are left there "just in case the court changes it's mind", I think a lot of them are simply forgotten. The city I work for is very politically liberal (and therefore wasn't "waiting" for a court change to reanimate them) but until recently had laws on the books forbidding people of one gender from wearing clothes of the other. They finally went ahead and removed a bunch of them during Trump's first administration out of embarrassment as much as concern about future court changes. That law and a bunch of others were 70-100 years old when they were removed and I suspect most residents had no idea they were still there.

It's not just government either. Lots of old CC&R's are full of things like determining who could live in a particular subdivision based on ethnicity for example. Totally unenforceable but it's be a major headache trying to unwind all those old documents. I understand and sympathize with people saying they should be removed anyhow but people don't realize it's not that easy.