This has been discussed many times. yes APT reject ~30% of all attempted transactions for customers signed up, and that increases to approx 50% for first time customers.
pigs, mado have constantly said APT sign up any bum and allow them to spend $. This simply is not true.
APT use
"proprietary real-time Repayment Capability Check"
details of the measures are unavailable but im sure mado/pigs would promote that the check is a flip of a coin rubbish.
ive added a couple of screenshots where 30%/50% rejection rates are mentioned..
one is from apt own report,
one is from submission to the senate economic references committee