It also makes me sad reading this thread. I too have walked the dogs around a storage lots attached to a campgrounds and wondered about the rigs stored there with expired plates. I even saw a couple with temporary paper plates that expired a couple of years before.
I talked with one storage lot manager who told me that a number of units were abandoned. The cost of getting the legal paperwork to take ownership of the unit for non-payment wasn't worth it such as out of state units owned by defunct LLCs or closed estates. She said the worst cases involved lenders who had written off units and wouldn't even respond to inquiries about transferring ownership.
There was a nice older class A parked next to us when we first bought our MH in 2007. I met the owners once. They were a nice couple in their 70s. It never moved for the next three years. We were back through there last summer and noticed the unit was still sitting there. The tires were flat and the curtains sun rotted. Every storage lot queen has a story.
When I look at the boats, planes, RVs etc. just sitting around rotting I'm reminded of how people in this country fritter away wealth.