Well, I'll take the contrarian viewpoint here (not hardly news).
I'll bet it has nothing to do with insurance, rather with big messes with poorly contained self-built RVs. I stayed at C.H.E. last winter, in the near-in area due to my van not being self-contained, close to the bathrooms and dumpsters. However, there were many RVs further in near the hills to the east.
Unless I am mistaken, C.H.W. has full hookups for RVs, but not C.H.E. So the RVs that were in the back at C.H.E. that did not have the best home-built full containment were likely making messes of some sort, probably tossing their grey water on the ground and peeing all over the creosote bushes. Such stuff builds up over the long term, so they probably decided enough is enough.
Also FWIW, I was a bit put off by the entire area. Very close to the border, and very isolated. The ICE facility north of Ajo is huge, and many ICE vehicles were continually running up and down the roads at high speeds. There were 6 armed muchachos, 4 sitting behind a concrete wall, when I drove through the checkpoint. Too much armament for my fragile puppy ego.