Not many people would realise that the 8 track cartridge uses one only reel to store the tape therein.
The tape is spooled out from the centre, around the PB/Rec heads before it returns to the outside of the reel. When new, the tape is loosely wound and it is slippery enough for things to work nicely. Over time and with exposure to hot and cold environments the tape tightens up and playback suffers. I think they're still used by analogue radio stations because they suit short term applications such as jingles and station idents. They've not been seen in car audio systems for a couple of decades
The Elcaset was a non-starter even though it was in the high end Hi-Fi outlets that I'd spend a lot of time in during my youth in the seventies;
I don't think you will find many TOTP episodes' sound tracks on these.
To put this in context; Betamax (a video cassette) lost out to VHS causing lots of folk to regret their investment in the format. Sony later released the mkII of Betamax in a smaller version that rivalled the mini VHS cassettes that became popular in camcorders. Years before, the Elcaset was launched to address shortcomings in the four track Compact Cassette. It was said that the larger Elcaset would give users of reel to reel tape machines an experience closer to what they got from full width tape reels.
It bombed Worse than Betamax.
Then Compact Discs pulled the rug out from both formats...
Now we're talking realistically about using DNA strings for data storage. It's amazing to witness all of that development in my own lifetime.
Wow. Just Wow - no flutter.