I don't know where the practise for installing light switches outside bathrooms, ever came from. BS 7671 only ever said at worst, that said switch should not be accessible from the bath, or always outside zone 2 in recent editions.
If you read the link about zones or volumes in France I set out in my post 45, it suggests class 1 light switches can be installed in 'no volumes', the same as our guidance of installing outside of zone 2. In fact its the same distance >0.6m from the edge of the bath.
Perhaps its diy'ers in France not following the guidance. The first link to a blog, talks about light switches in France being installed outside the room its for, including bathrooms.
As a lot of UK bathrooms have a quite small floor area, sometimes the only way to achieve the guidance, is a pull cord or switch outside, unless you live in BP and have a bathroom the size squash court.
Time for bed soon