As a vintage car fanatic for 40 years, I'd generally agree with the observation on GM '60s vs '70s/80s, (though '60s fit and finish was nothing to write home about either and 60s GM frames are notorious rusters). However a great deal of the reason for '70s/80s car issues can be attributed to the fact that all the US companies got off track when stricter emission and safety laws forced them to devote resources and time to solve that problem. Those great '60s cars had PVC and that's about it. They became increasingly cantankerous starting around '72 when simple exhaust gas recirculation would no longer meet emissions standards that tightened greatly every year up through the '80s. Safety bumpers etc made them heavier and more ponderous. Our '57 Lincoln, '70 Fury convertible, '70 Nova and '71 Fury III still start and run extremely well, as have many other '30s up thru around 1971 cars we have had. I won't buy a '72 or later vintage US car. Around '72-73 driveablility and durability started to slide drastically, leaned out carbs had poor driveability and engines were intentionally run hot. IMO mid '70s GM cars were cranky inefficient whales. We had a 73 Delta 88, 74 Delta, 75 Delta, 76 Olds 98, 77 Olds 88, 78 Electra. Loved the ride but mostly they couldn't get out of their own way. The '77/78 weren't too bad, much improved. Volvos and Saabs after that. I'm not sure any analogy re: GM can be carried over to appliances, however. Any appliance quality control issues were more than likely divisional bean-counter decisions. GM divisions were highly autonomous in those days, even the car divisions had their own separate frame, engine and transmission designs until about the late 70s, though they had shared Fisher bodies going back to the 20s/30s.
Seems there are diverse opinions here about Frigidaire reliability!