Gotta love the clear coat.

So, if the clear coat failed, where'd the rust on the roof come from?

Many "base" coats no longer have the same UV protection as single stage paint offers. The clear is supposed to provide the UV protection. After the clear coat checked and started peel off, the base coat started to follow it. The paint on that car was done by a con artist "flipper", some places it had original paint straight under it (you can see the "petty blue" in some places in that same picture), other places where they sanded through was just metal. When the base coat checked the bare metal flash rusted, as it does. After, not before. When the base first started checking the metal below it was clean.

Sure, that clear was not applied properly. But I've seen plenty that was done right peel off just the same. Single stage is far more resistant to application issues than base-clear, even the "good stuff".

And if you leave your car outside all year round, I really don't know what you should expect after 5 years of the climate beating on it.

Well the Summit brand single stage, low VOC California complaint paint I sprayed myself on the front clip of my Duster has held up just fine, and that was 5 years ago now. So yeah, I expect at least that. I've done that paint no favors whatsoever and it still looks as good as when I sprayed it.

I work for Sherwin Williams Automotive paints and I can tell you there are so many knock off cheap clears made in China and everywhere else that's what you get with no maintenance, wax at least twice a year. Yes paint jobs need to be feed. The new glamour clears are exceptionally good and all of the good brands charge for them. PPG, Axalta, Siekens, Sherwin Williams, BASF etc. You will pay $500 - $700 for a gallon, a quart of hardener and a qt of reducer. All cars are now base coat clear coat and all repairs are done the same way. If you want it to last then spend the money, if not buy cheap and get 3-5 years out of it. Just like anything else you get what you pay for and being uneducated is not the way to get your car painted or it may look like the pictures here.

Like I said, 5 years so far out of my Summit brand single stage, low VOC, "cheap" paint that I shot myself. Looks just as good as when I sprayed it, car's parked outside. No wax either because there's gonna be another paint job eventually and it won't go back to bare metal so no wax to keep it from contaminating the next layer of paint. Whenever that is. Yes I know that's not the way to care for paint, but it's a work in progress not some garage queen so sacrifices are made.

Being "educated" doesn't just mean buying the most expensive paint and spending a fortune to have someone else spray it for you. If you really know much about paint you can figure out that there are cheaper alternatives that will hold up just fine, because like a lot of things some of the "cheap" stuff is just re-branded name brand stuff. Paying more money for the same paint does not make you smart.