That is amazing to me. In Minneapolis, everyone requires you to remove shoes before entering the house proper. Maybe it's the snow ... of which we are currently in the process of getting about 12" tonight :-/
During the rest of the year, it depends a little bit on the residence. I never cared if someone kept their shoes on in the junky apartments I lived in during college, but if it were my parent's well-kept house for example, I'd consider it rude to keep them on.
One of my friends has such high carpet and a close to the floor door that they can't have a rug immediately inside their unit. They contrived a mini parkour course to safely enter. You'd have to hop from the common hallway to a rug 2ft in and then to another one 2ft further, all in the name of etiquette and not wearing shoes "inside".