We talked to the guys in the gas station and they were both adamant that the station was not responsible -- both Javier and Victor, independently. They both said that they hated them and had nothing to do with bringing cars in.
Apparently ( according to them) it is all down to people living up the hill mountainside who reckoned they had to wait until they could turn left without looking. It appears that if you do not look, and own a very expensive property above, the car gets hit.
So. It would appear to be an illegal fixture on a state highway - along with the runway lights. So let's just dig them up.
I think they tried this a year ago with tarmac topes -- which got pulled pretty damn quick.
Who knows who to complain to?
Or who knows a cheap JCB driver?