Went back there a couple of years ago (moved to San Diego in '65, left in '06) and I was amazed at the number of ratty old motor homes of both C and A types sitting on the side streets downtown, on Fiesta Island, in OB, and on Harbor/Shelter islands by the bay. I can see where the reasoning for the law started.
Let's face it, the "RV homless" probably don't always find a dump station when they need it and the nearest stormwater drain looks mighty tempting. Plus it just plain looks pretty ratty to visitors to have some of the junk I saw rolling around parked all over. As a full time resident you may not have noticed the slow increase in the numbers but coming back after being gone for 5 years it was pretty obvious.