APS was a compromise between several camera and film companies. Thus you can say, like the old saying, "an elephant is a mouse designed by a committee"!
That said, I saw, while doing R&D at EK, a talking photo system and a 3D photo system. Both were quite interesting but never got incorporated into APS. The talking option was considered due to the magnetic stripe.
The different formats were the same size on the negative, but the viewfinder showed a different format. The format choice was recorded on the film and then the printer adapted to that information to print one of the 3 formats.