Broken Glass
I've seen broken glass at most of the sites mentioned and have wondered, "Was it a break-in, or did someone smash the window because they locked the keys in the car?"
At 19 Mile Brook there was a car with the window smashed and no one was around, I guess it was safe to assume that was a break in.
We did a sunset trip to the Sugarloafs once and when we came down there was a bunch of kids hanging in the parking area, no hiking or camping gear. I think we may have averted something there. I should have reported it.
I guess the only safe thing safe to do is to leave nothing in the car, the glove box open and the doors unlocked. Not always possible, I know.
KDT