Yep.. Sure is..
There can be many reasons behind what they do..
Up here it's taxes.. Up here in alot of counties (yes we have them to), the property taxes definitiion of permanent structure = living quarters. And once a "permanent structure (ie living quarters)" is on your land, the property taxes are thousands of dollars vs a couple hundred for an RV with carport. Silly, but I know what i would do. Not to mention the protection from the elements..
Up here our season is very short (2-3 months), and using an enclosed "car port" around the trailer, lengthens the season.