In message , NY
writes

I'm baffled that people can ever manage to reverse without lowering the
mirrors when the only reference points are lines/kerbs at ground level
rather than waist high hedges or walls.

What did we do before lowering door mirrors were available? There are
probably quite a lot of people reading here who started driving long
before door mirrors were fitted to cars. It was not that long ago when
the only mirror was internal. No door mirrors, and no wing mirrors.

--
Graeme