I was clicking through various and sundry websites depicting retreat cabins, and it struck me that they are all more or less the same. The one pictured above is located on a private wildlife refuge out in the Mojave Desert.
This one (check the center of the photo) comes to us from Don Croner, and is found above the Aryaval Temple, north of Ulaan Baatar.
These are the Dru-gu retreat cabins, near Dru-gu Monastery in East Tibet. I guess retreat cabin architecture is instinctive. Either that, or people just naturally think a tan box with a window and a door is the way to go.