You just never know what people's personal circumstances are and it could be due to any number of reasons like health, financial, family issues, work commitments, etc. and the owner could be hoping/planning to get it back on the road one day. The owner could have quite the total in storage fees. I look at that photo and don't see a camper - I see leaks, rot and mold.
Being in a rural area, there are lots and lots of RVs parked on properties around here out in the open that haven't moved in many years and have plenty of dirt, algae and cr#p all over them. Some people sure have different strategies/ideas/plans for long term storage.