I suspect one of the drivers behind Mode S is so that we can share our uncontrolled airspace with UAVs. They don't say it, but I bet that is a reason.
The whole thing makes me want to vomit. I shall not switch it on most of the time. As I have said before, what are they going to do? Send the police to the rough area where my non-mode S transponding aircraft disappeared from the screen and try and arrest me?
Add in number plate reading cameras and face recognition cameras all over our motorway system (now and in process), aggregation of all medical records to a cetnral spine (in process), road charging by GPS transmitter (trials planned), guarding of all mobile phone calls and location information for 5 years (now) and, boy, do we have a surveillance state.
QDM