8 Tracks are like a B school lesson in finding the "almost good enough" solution to a problem. A combination of ingenuity, hustle, self-deception and fatal compromise. Funny and failed like a leisure suit. As an art project, though, funny and obsessive. Designers love this stuff. And those green 8 track shells mentioned in the Verge article were because the label was "Chrysalis". Dig it.
ArsTechnica did a capsule review of the hardware history of the 8 track. Carts - in the sense of the NAB cartridge, both preceded and survived the 8 track.
https://arstechnica.com/gadgets/2017/01/forgotten-audio-formats-stereo-8/
But the 8 track was the 8 track because of the people who cobbled it together and could look you in the eye and tell you that the 4 track tape is dead and the Philips cassette is a toy and if people are driving with the windows down they might not even notice that the song faded out weird.
Everything 8 track over here - http://www.8trackheaven.com
In the suburbs just west of O'Hare in one of the first industrial parks was the home of Ampex. There is a first person account from a guy who worked there in 1971.
http://www.8trackheaven.com/archive/ampex.html
The brief success of 8 tracks also played a role on reshaping the record business. Ampex had successfully negotiated distribution deals with many labels at a time when distribution was still mostly small labels with independent distributors servicing territories. The Ampex model of a national organization was influential when labels started consolidating and moving to branch distribution (CBS, WEA, MCA, etc.) in the 1970s.