Peeled or cloudy clear-coat can be from a bunch of things. Constant sun exposure does not help at all. I've had quite a few cars and only a couple were garage kept. The rest lived under the sky all their life and none of them had a problem (however, I waxed them 2x a year).
I tend to think that defective paint or flawed paint jobs are the major culprits. Factory clear-coat defects can -and do happen. Local auto/body shops screw-up paint jobs all the time. Also, if someone goes crazy with 1200 grit polishing compound (like meguire's #105) and a 7" microfiber pad at 6,000 RPM, the clear coat will get cut down significantly. Once it's ultra-thin like that, the sun will take over and finish the job. A properly done paint correction will reduce thickness by around 5 microns and most cars only have 70-100 to start with. An idiot with a buffer can speed-up wear & tear like nobody's business.
Ray