Health check raises 'usual GP' question

Recently a kind and patient person from my general practice division guided me through the murky and confusing waters of the simultaneously new, old and disappearing GP item numbers.
Apart from the countless nuts and bolts involved, a few issues deserve special mention.
Firstly, patients will rightly be the winners of the November 1 psychologists’ access to Medicare, but employee GPs registered with Better Outcomes and who took home their SIP payments will be among the losers.

Patients of this group of doctors - and I admit to a conflict of interest here, I’m one of them - already had free access to six to twelve psychologist sessions via ATAPS (Access to Allied Psychological Services) if a mental health assessment and plan had been completed. On top of the associated consultation fees, a $150 SIP was paid to the consulting doctor after the third visit under the scheme, which will wind up in April next year.
Overall, however, the move is a probably a good one for the mental health of the community. After all, why should access to a psychologist depend on how many hurdles your GP’s jumped?
Nonetheless, I was glad to learn that other SIPs, such as those for performing a pap smear for women not smeared for over four years, will remain in place, as I fail to see how an incentive payment can be an incentive for someone who doesn’t get the payment.
Equally interesting, or annoying depending on your point of view, is the arrangements surrounding the new 45- 49 health check.
A call to the hotline confirmed it’s a once in a lifetime check to be performed by your ‘usual GP”, defined as the GP you’ve seen most frequently over the previous two years.
But just as patients who pop into a medical centre with a sore toe on holidays end up unwitting recipients of care plans, now they’ll likely end up with the only rebatable health check of their lives by a doctor who’ll never see them again.
My question is this:
How is it that ACIR can identify ‘usual GPs’ when it comes to withdrawing PIP payments for practices who’ve slipped below an immunisation target, but when it comes to rewarding doctors for performing a preventative health check, it’s suddenly too hard?