If you grow up in a clean country that isn’t very muddy outside, you might not ever notice the need to change shoes in something like a mud room. But spend one winter in Beijing (or Eastern Europe or basically anywhere in the non-fully developed world), and it became really obvious to me why you need indoor and outdoor shoes, and why you have to thoroughly wash your face a few times a day.

That being said, conditions that you are used to will influence whether or not you believe shoes have to be changed between outside and inside.