Drawing faces; why I don't

I've had a few queries recently regarding 'seeing' faces and drawing them:

I really do 'see' as I imagine everyone else does. Cecilia Burman's wonderful, straightforward site (prosopagnosia.com) describes the level of similarity of faces as being equivalent to telling rocks apart - unfortunately this seems to have been misinterpreted as the direct visual experience. It's not. It's just the identity that gets lost - if you've got a big nose, rosy cheeks and a mean glint in the eye I can tell that fine - I just might not know who you are.
It is just my inability to process those features as anything more than they are. They just don't register as being someone. So again - I can draw noses, ears and eyes. However unlike my mental picture of a room - where the residual image would be very intricate and I could peer into corners and see decorative details - with faces I can't remember anything about them. It's like looking at a very blurry gif in my mind. Just a grey blob. So obviously I just draw very crude approximations. Which is frustrating - and if I ever draw faces from memory: they just look like cartoons.

Weirdly even when someone is sitting infront of me I find it very hard to generate a likeness because my brain can't seem to retain the relational space between features. I might be drawing the eyebrows perfectly because I am looking directly at them but then I pull back and look at the drawing as a whole and they will be out of proportion or relation to the rest of the face. So the face becomes a distorted mess even though i can draw what I am seeing. Still annoying - but so much nicer now I know why...

Any way this is why I tend not to draw faces and to focus on details that I can happily manage like hands, or hair, or clothing. Course I could just be rubbish.