I don't know how you'd confirm either way. A lot of stuff from the 80s is in landfill now because it's just old, even if not broken.
I'm sure we built a lot of badly made stuff then too, but my guess is with our tighter manufacturing tolerances, we can push things closer to breaking point, with our increased casting/molding tech, we make stuff smaller and more complex, so it breaks more, we also drive harder to profit margins (unsourced claim!) so cutting corners/quality is more acceptable/planned obsolescence/planned failure.
I'm sure we built a lot of badly made stuff then too, but my guess is with our tighter manufacturing tolerances, we can push things closer to breaking point, with our increased casting/molding tech, we make stuff smaller and more complex, so it breaks more, we also drive harder to profit margins (unsourced claim!) so cutting corners/quality is more acceptable/planned obsolescence/planned failure.