I grew up in Texas. I understand your confusion. Houses are oriented a little differently here, but think of the “mudroom” as the garage. You know how you have a side door and a front door? And the side door is usually sort of attached to the garage, basement, or maybe laundry room? It is just that. A lot of people have a spot right inside that door, off to the side, for piling shoes. Otherwise you have a rack when you walk in, or you can use the closet right by your front door. It isn’t really a separate room. Good idea to have mats on both sides of the door. For whatever reason people are obsessed with split levels up here, so there is easier access to basement type areas.