At the time, walkmans were trending: people would use recording devices to record the song if it played via the radio or at a concert. You would know at least one friend who has a legit copy (vinyl or cassette) “borrowing” that for the purpose of pirating music, in which that finished recording is replayed on a walkman to listen.
The invdividual uses a voice recorder, the ones with cassettes to store audio but what could happen is that you can capture other audio cues irrelevant to the song (door opening or people speaking in the background). It’s kind of volatile in that sense, unless you are in a room that’s dead silent and soundproof capturing the audio.
What do you think all those dual cassette decks were for?
So you could make friends a copy or copy friends’ music.
Perfectly acceptable at the time. Only an issue if you were selling them, but even then not a huge issue.