, 1090es is the equipment of choice in Australia and most all of the known world. UAT is site specific US and small parts of China around training facilities.
Equipment of whose choice, I don't recall being asked for a vote on choice.
And arguably the 2 most trafficed nations on Earth U.S. and China have chosen UAT, now why might that be ???????
1090ES the VAN 5 of modern aviation data communication.
China is emerging as a major player in Aviation as its population would suggest it should.
On a different note the capacity of the transponders on the new NBN satellites wil be adequate to carry the data traffic for UAT, without any compromise to their primary function providing Broadband for remote communities.