I mostly fly gliders, from which you have clear vision of virtually all of the sky, and also have "lookout" hammered into you from the first lesson.
Every time I climb into a single engined Cessna the almost total lack of vis scares the sh1t out of me - the lid overhead & in turns, no vis ahead & below (engine), huge door pillars/structure (I'm sure this applies to most high winged a/c, not just Cessnas, but there's more of them).
Any person who flys little other than one of Mr Cessna's products (and presumably this covers a large chunk of the UK GA population) has probably got used to this obscured vision and probably doesn't realise any more how little of the sky he/she can actually see.