I think it's an insurance policy. If they don't post the signs like that, they would be open for a lawsuit if somthing were to happen. I know that quite a while ago they use to allow it, but it was abused and they couldn't afford the insurance bill so they changed the policy. As usual generosity was taken advantage of.
They have a lot of RV's setting up shop overnight. Not a good look for a big business.
Because they have there trucks and cars r harder to see at night without headlights and there trucks would be liable for the cars damage
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