PBS isn't about kickbacks, it's just lower price Medicine.

Trump specifically hates our PBS since it 'hurts American pharmaceutical companies' yet the actual US pharma companies love it, since it's a reliable customer

You can see the prices we pay for medicines- https://www.pbs.gov.au/healthpro/explanatory-notes/front/fee

For most medicines in Australia, it's $25, or $7.70 if you have a concession card (HCC/DVA Gold/RHCA), Pharmacies get a set dispense fee (unless it's a dangerous medicine or needs to be compounded, which just add extra set fees) and the Pharma company gets a fixed negotiated amount paid from taxes.