My grandmother has indoor shoes (just like the schools)
When I was at school, we had to have house shoes. We were told it was for hygiene reasons, but later on the rule was dropped, as there were two builidngs in the school, plus a gymnasium block, and and what I swear was an old Army hut used as a dining hall, and girls switched between the four sites without changing shoes. And the staff didn't wear house shoes. We were not allowed to wear them in the gym when we had House Assemblies there, as the gyms were used by girls in bare feet, and so the hygiene rule applied there. We left shoes in the changing rooms.
I've only ever been asked to bring slippers to my cousins' house, as they had just got new carpets. Unfortunately, those I brought were a Christmas present from the day before, and I had not tried them on, and they turned out to be too small, so I had to borrow a pair of thick socks to keep my feet warm. I took a pair of slippers that fitted the next time I visited, and a good job too, as we had been graveyard hunting for ancestors on quite the wettest June day we had experienced in a long time. Otherwise, I have been to barbecues there and everyone slopes in and out of the house and garden without changing shoes.