I guess we need to distinguish between legislation, regulation and case law established through judicial precedent. Legislation is definitely too cumbersome to react to shifting moral standards. Regulation and judicial precedent are more flexible in cases where legal consequences are warranted.
As so often, there is nuance to the topic. General statements are hard to make both concisely and precisely. I opted for brevity, but you are absolutely right.
Either way, we agree that complacency about CSA is fucked up.