Because you simply don't need it out in the GAFA, traffic at Mildura = nil Port Augusta = nil Ceduna = nil Forrest = nil Kalgoorlie one other aircraft doing touch and goes.
Traffic density overall bugger all !!!!!!!! in flight did not see one other aircraft, nil, nada , none.
That is the joy of free movement in G airspace below 10,000 at VFR hemispherical levels.
Now UAT weather up link in the Continental U.S. in tricky high latitude weather, now there is a sweet system, ADSB again no need just the uplink services, great safety tool on approach to Minneapolis/ St Paul on a dark Autmn night with CB's about.
Out in the Australian GAFA on a VFR gin clear day absolutely no use what so ever, in fact a distraction rather than a assist. Look out the window it just might keep you alive.