So you could play tapes back-to-back of course. Any decent system could pause the second deck until the tape in the first got to the end, auto-stopped and auto-unpaused the other side. That was an almighty kaCHUNK noise when it happened though so you wouldn't want to be a light sleeper trying to sleep to music with it.

There were also logistical problems with how you chose to play tapes, especially if part 2 of an album was on the other side of a tape.

Or you spent an absolute fortune on a deck that could play the other side without needing to take the tape out. They didn't make many of those.

But yeah, I get your point, one side of those double decks could also record from the radio or the other tape. Which is why in some countries taxes were levied on blank tape media to "reimburse" the poor, struggling music industry for the rampant piracy, where curiously, literally none of that went to the artists. Hmmmm.