Just like THE live album of the late seventies, Frampton Comes Alive (every household had one), features audience applause from a Grand Funk Railroad gig, probably even from their first Live album.
Or how two of the tracks of UFO's famous Strangers in the Night were recorded weeks later in the studio (though "live" there) and then adorned with audience noise by producer Ron Nevison who is to this day proud of the fact that he matched their live sound so closely.
Next thing we know, Elvis didn't laugh on those live recordings either ... Which track was it again? "Are you lonesome tonight?"?
During those Cash prison concerts, security was tough. Had the inmates cheered at Cash singing about the murder of another guy, I'm sure the authorities would have threatend to pull the gig (and prompted a riot!).