Having been detecting since the 1970s, I have seen the whole thing "evolve", at least as it pertains to state-of-CA owned parks near me. Believe it or not, there was a time when the issue was never given a second thought. Bear in mind, things like ARPA (1979), and general "archaeological awareness" are fairly new things. We just never knew any better, and figured "parks are where you detect. Afterall, they're public, right?" If no one ever said anything, why would we have even thought to ask. Things were fine

But then fast forward to the 1980s, and someone new says "I thought you couldn't detect at such & such?" Us dumb oldtimers would say "since when?" Turns out they'd gone and asked! Funny, but we'd never been bothered in full view of anyone and everyone. And from there it snow-balls: The continuous inquiries/attention only made rank-&-file parks persons "aware", since they had to root around in minutia to answer the inquiries. Yet before, never gave it a second thought when/if they'd seen someone previously. And you can see how this evolves
Another example, if you talk to guys who hunted civil war artifacts back in the early 1960s, with primitive BFO machines in the CW areas, they will often tell you that, back then, you could go to toe-curdling sites, like Shiloh, Ghettysburg, etc... and no one would pay you any mind. A detector was a novelty, and you were just looked at as an innocent odd-ball. But I venture to say, that even in the early 1960s, IF those same persons had asked enough questions of enough bureaucrats (after all, there were archies even back in those days), they'd probably have found out that
technically, even back then, they'd have gotten a "no".
So quite honestly, here in CA, if I/we know of a state park that "no one cares", we don't rock that boat. Technically, I think there may be rules about "over 50 yr. old coins" and such nonsense. Heck, one archie even came and hassled a guy on a state BEACH here! A few persons on our local CA forum thought about "fighting that", but the conclusion was: "Right now, no one cares, except this one random event, so the BEST thing to do, is treat it as an exception, and NOT bring attention to ourselves" Ie.: "keep going and don't ask dumb questions"