One reason, I think, was a giddy feeling in the late '70s that the End was Nigh, so everything was permitted and there was no reason to compete.
Everything was allowed in the late 1970's.
Nothing was allowed in the 1970's!
police are working.
A cat catches a mouse.
A young man is at the bingo table.
A person driving a car down the street.
people with their backs to the camera have pink posts on their backs
It was simple, and they figured out exactly how the law applied to it.