Auto exposure of film is a solved problem since several decades ago. It was built into the cheapest point-and-shoot cameras, and performed pretty well, at least in daylight. I think the issue here is the film, poor latitude, stability, and qc in general? I guess it's some kind of a miracle as it is.

True enough. I think the point I've seen made in a couple of places is that either the components are of the lowest quality under a slick outer shell, or they have been incredibly poorly set up for use with instant film. Or both.* 

Yes, everything you say about the film seems correct, although it's pretty piss-poor if a company at the forefront of film technology like Fuji cant get it right. And yet I've seen artefacts such as a starburst of white at the corner of some shots caused by poor chemical dispersal as the film is ejected, which is just crap.

*I take your point, in fact I think I said something similar at the start of this thread. That said, I am deeply suspicious of just how badly some of these things work. I mean, the basics of decent sounding medium priced music systems were known in the 30s and 40s, but that didn't stop Bose building speakers out of dollar shop speaker-units in budget chip-board boxes and snazzy vinyl wraps. A ton of pseudo-science and they convinced half the buying public that they were the bees'-knees of music reproduction.