@gerard
No, I'm 40 or so
you'd be surprised what recordings people can get their hands on. For example, I have a soundboard of a private concert that Sinat ra gave for Nixon at the Whitehouse that was somehow sneaked out.
The Watergate guys, perhaps?
I have hundred of unreleased shows by various artists going back to the 1940's. And people did just like you say - they waltzed into venues with reel-to-reel recorders. No need for iphones.
People always recorded Buk - for example, you can see a couple of people put tape recorders on his desk as he reads during Last Straw.
there must be stuff out there.
R