That’s because average residential construction has some tolerance for error (and is therefore poor quality imo).
Sure - perhaps not plumb to within +/- 0.001 radians, but there’s still an expectation that the wall needs to be vertical within some error tolerance band (even if not specified). Error correction happens real-time - the cabinet guy compensates for the wall error, and so on.
That’s also why I find residential construction so shoddy (the US at least) - electrical junction boxes are always a little off-angle, cover plates aren’t flush, etc.
Sure - perhaps not plumb to within +/- 0.001 radians, but there’s still an expectation that the wall needs to be vertical within some error tolerance band (even if not specified). Error correction happens real-time - the cabinet guy compensates for the wall error, and so on.
That’s also why I find residential construction so shoddy (the US at least) - electrical junction boxes are always a little off-angle, cover plates aren’t flush, etc.