After looking at the video that was in the thread you linked I have concluded that you are in fact correct. These people were being very silly.
The Cameras are indeed attached to a pole that has multiple heavy conductors running to it. The Cameras are clearly marked as part of a SCADA (Supervisory Control and Data Acquisition) system.
What we have here are people who desperately want to believe there is a massive conspiracy controlling the government and that the government is intent on spying on them. (Like they couldn't do it with satellites.)
I am very familiar with the type. They imagine boogie men behind every bush. Nothing is what it seems, and everything points to government conspiracy.
They espouse a severe form of "confirmation bias." Everything they see is looked at in such a way as to confirm the theory that they already wish to believe.
This is the sort of hot-head, knee jerk, reactionary behavior that hurts rather than helps their cause.
There used to be a cartoon TV show, King of the Hill. One of the characters, Dale Gribble, saw a government conspiracy behind every bush...but could never figure out that a neighbor was in bed with his wife every day. I found it funny.
Similarly, as you pointed out, the government has very accurate sat cameras, high flying surveillance aircraft, etc at their disposal. And, if the government wants to monitor comings and goings on a road, they probably could do a better job concealing a camera somewhere along it.
Its possible this group of Dale Gribbles was in fact being spied on, as they were taking apart their ‘spy camera’ find.