I think it totally varies. Gloves are not common at all in my experience in Europe. Even the SAs at FSH handling jewellery did not wear gloves. Not seen them in Germany, France or Spain.
However (and rather strangely), the SAs in Manchester Selfridges do use gloves when handling bags and jewellery. Manchester King Street do not. So it must be an individual store policy thing. I personally found it strange. But then I'm not used to it...
Do you think it is because the staff in H Selfridges are new and therefore just to be "on the safe side" they use gloves to prevent scratches to bags?
However when I collected my new bag from King Street awhile ago, they did put on gloves to show me the bag, which I was really surprised at