It's cultural and (possibly) geographical. Our American neighbour, from Washington State, is still adjusting to the "no shoes" rule. She's adapted by purchasing a big shoe rack for the front door. She speculates that the Canadian habit to dress for the weather makes entrances and exits to our own homes a ritual, where hat, mitts, scarf, coat and boots are regularly shed. I'd NEVER walk in to someone's house in my street shoes, as our winter streets (and most of spring as well) are mucky with sand and snow and salt and silt.
MrsMcDucket, just in case you were wondering, we rarely go barefoot in other people's homes. We got socks.