10 year rule, I figured it out

I keep meaning to take some pictures but here goes pictureless. Here in the Seattle area, there are a lot of people living in old decrepit Class A's, Class C's and the odd TT or 5th wheel. There are parts of the city ie Ballard, Crown Hill, where there is mixed industrial / residential and there are blocks where there are several parked per block. Seeing these rigs, I can fully understand why some parks use the 10 year rule. Some of the private parks around here have a "older than 10 years subject to management approval". There's a guy with a camper in the back of a Ford Ranchero, and in front of Ivar's Salmon House, a Seattle landmark, there's a converted bus (the kind with the woodstove pipe venting out a window covered in sheetmetal) that must move up and down the street just enough to keep from getting impounded because it's always on the street in that block.