Go ahead
Then go ahead and put it in. But do not make it compulsory for people who do not wish to go there. Don't try to con GA people by giving false information about proposed subsidies, and the benefits thereof, and what the equipment will do. Do not legislate to give a monopoly to any particular company.
Most GA aircraft have been fitted with transponders, and many have never been anywhere near controlled airspace. These and other owners/operators are wary about further mandatory expense that is only there to benefit ATC and the airlines. Who will service ADSB out in the bush.? The transponders we fitted were a maintenance problem, and hardly ever were of any benefit to us in Alice Springs. Mostly we could not even tell if they were working properly.
I think ADSB is the way of the future but unfortunately it is necessary to make lots of noise to get some reasonable behaviour from our aviation authorities. GA aircraft (below 5700 kg) outnumber airliners by about ten to one, and must be given proper consideration.