I know why you're suggesting that, but it's purely anecdotal.
For instance, Arstel offers 4 under their own brand (probably rebadged Alcatel), 2 each for Motorola and Sony Ericsson, 3 each for Blackberry and Nokia, 6 each for HTC and Samsung (2 of which are Galaxy S II variants), and 7 Apple (6 of which are 4S variants). Of their prepaid phones, there are 5 branded Telstra and one each of HTC, Motorola, Samsung and Apple (3GS).