The Irish had their chances against a Wallabies side that contributed equally to a forgettable encounter, which was in the end decided by a pair of first-half tries from the hosts.
It was an Ireland error that allowed Australia their first try against the run of play when Luke Burgess intercepted an errant pass from debutant Chris Henry to race over.
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Hide AdA rare moment of brilliance from Quade Cooper, who punched a hole through the away defence on the stroke of half-time, then gave Australia a 16-15 half-time lead they had been lucky to hold after Jonathan Sexton's steady boot had ensured the Irish a firm grasp in the game.
But with the tourists unable to break down the Wallabies after the break it was their defensive errors that proved costly and Kidney conceded they deserved to end their three-match tour winless.
"We made too many errors, especially when we were attacking, and that was frustrating," Kidney said.
"We defended stoutly but that left us short of energy at the end when we were trying to claw something back – in the end the result probably flattered us.
"There is now more competition for places and whoever plays well next season will get to wear the shirt."
Scorers: Australia: Tries: Burgess, Cooper. Pens: Cooper 2, Giteau 2. Ireland: Pens: Sexton 5.
Australia: J O'Connor, D Mitchell, R Horne (K Beale 40), M Giteau, A Ashley-Cooper, Q Cooper, L Burgess, B Daley (J Slipper 54), S Faingaa, S Ma'afu, D Mumm, M Chisholm, R Elsom, D Pocock, R Brown. Subs not used: H Edmonds, M Chapman, M Hodgson, J Valentine, B Barnes.
Ireland: R Kearney (G Murphy 53), T Bowe, B O'Driscoll, P Wallace, A Trimble, J Sexton, T O'Leary, C Healy, S Cronin (D Varley 70), T Buckley (T Court 40), D O'Callaghan, M O'Driscoll (D Tuohy 71), N Ronan, S Jennings, C Henry (R Ruddock 68). Subs not used: E Reddan, R O'Gara.