You can pay 9.65 GBP for a medicine that costs the NHS 0.10 GBP or 1,000 GBP to buy. The idea is that the flat rate evens out the cost for everyone.
The Australian PBS system is a terrible one for patients, especially for those that need medicines that aren't on it & have to pay full price for them out of their own pocket. Every medicine that the medical profession says you need should be on the PBS, not decided by politicians & accountants. Worrying about finding $10K year to buy medicine when you're seriously ill & unable to work is the last thing you need.