When..radio stations were airing spots or commercials, they were on short length broadcast carts. The audio cassette became popular due to its small size and longer record/play times. They became popular in autos because the machine itself was alot smaller as well as the media itself.
Now everything is digital in nature. It is quickly retrieved, no signal degradation and of course smaller. However digital as we know it cannor compete with analog from a physics point of view. Almost all digital record/storage recording systems are comprimised in what they record. Any open reel recording will sound better than MP3, etc.
I was a sales engineer with Ampex Corp in San Francisco for 20 years covering the NY recording studios during it's heyday. Ampex (google it) was responsible for the audio recorder as we know it and later invented the video recorder. The audiotape division was the preferred product with engineers and producers the world over. We also had another division in Illinois that was the worlds largest 8 track duplication facility. Almost all domestic 8 tracks came out of our plant.
When digital storage gained traction in the late 1990's the recording tape business just about disappeared and I left the company to pursue other interests.
I left the original cassette and in dash radio stock in my 1980 SWII. I updated the 4 door spkrs to 5 1/4". I designed a CD/rcvr/USB component box with a veneered face and leather trim to fit between the factory center setup and the floor . I also designed a similar cab that sits over the floor tunnel in the rear pass compartment that house 2 6x9's and an 8" subwoofer. The trunk storage well houses 2 large Pioneer power amps. The new additions in the car can be unplugged in under a minute, flip a switch and the system goes back to 1980 in function and appearance.