I think you are overly concerned about something that rarely happens. It is just not something reported on here very often at all. Not to say it can't or doesn't happen, just not something to dwell on. Commercial RV parks and national/state/COE campgrounds are of very little concern.
Having said that, if you camp at remote unattended campgrounds, or stay in remote areas of truck stops, or parking lots with little to no late night traffic, then there may be more concern. In the campgrounds, just put things away at night so that they can't easily walk away. In parking lots or truck stops you shouldn't be putting anything out any way.
We have never had anything stolen in all our years of RVing. But we do not do remote unattended campgrounds, truck stops, or parking lots.