So is your issue not what they are doing its where they are doing it?
Thing is sometimes as a driver\rider we may not realise that others may come piping thru.
where I live there is a road that goes through our estate joining two B roads, and vehicles come through as if they are on a track. The residents are full of kids including mine and during summer they are out in force. One might think clearly this is a built up area, no one will dare speed, so no need for enforcement.
I guess one can argue do you wait until someone gets knocked over then to decide, right its a point of concern let do something, or if you see its starting to get hot you try to do something about it.
Why do you think there is not concern for speeding in the area where they are camped out?