Hey there maxx-katt, as someone who's been into this since the 1970s (started as a teenager in Jr. High), I can comment a bit on this
There were definitely a few forward thinking hunters who cashed-in on virgin sites. That can regale you with stories of silver in the parks, blah blah.
But you'd be surprised how many persons (myself included) who weren't that forward thinking. We were content to just ply the school yards and junky parks, looking for merc's and roosies and wheaties. It never occurred to me, back then , to do exotic things like stage stops, beach erosion, old-town urban demolition , etc.....
Not that I didn't occasionally try. But when a few "pesky bullet shells" surfaced, I grew bored, and left for "greener grounds" back at the elementary schools that "didn't have as much junk". Looking back, I realize now, that the bullet shells were rimfire henries, that should have given me wood. Doh! And decades later, I would return to the exact same sites and find reales and seateds. Doh !
Just didn't understand the relic mindset. And I have seen the same attitude , with 1960s and '70s hunters that I've talked to. They were content to do sand volleyball courts, etc.... It never occurred to them to do ghost towns, forts, etc.... (too much "junk").
Bear in mind that discriminators didn't come out till the mid 1970s . And weren't in popular use till the later 1970s (slow to catch on in the pre-internet era). Thus foil, lead, tabs, etc... were a big problem. And bear in mind that the machines back then didn't go too deep either.
Yes I'm sure there were people who were forward thinking, and understood "good junk", etc....
I can recall that I never even found a seated coin till the early 1990s, despite having already detected for 10 or 15 yrs. by then.
So as virgin as things were in those days, there was a lot of un-exploited ground. And even today, it amazes me what sites (when I travel) that have not been exploited.
But a sad truth to the 1970s and '80s, is that .... yes .... the easy silver in the parks is gone. I pity the persons who go now, and try to get silver out of some of the parks that used to be our stomping grounds . I would not touch those parks with a 10-foot pole now.