I was also horrified that my private health insurance didn't cover any of the radiation treatment costs. It was explained to me that it wasn't covered as you needed to be admitted as a patient (day patient or overnight), and this didn't happen with radiation treatment as you are in and out, thus my private health insurance wont cover any of the out of pocket expenses -shame on private health insurance funds!.
I had a discussion about my financial situation with the private radiation practice I was refereed to, as I was going to move into the public system for radiation, but they reduced my out of pocket expenses without hesitation to a very small amount. They also billed medicare directly so there was no stress in paying or claiming. I've only just finished radiation treatment and medicare covered approx $17,000.
Not trying to defend the costs charged, but I was happy to make the small contribution to my treatment as the radiation technicians have many years of training, the doctors are specialists, I had constant access to a nurse and the high level of machines used cost upwards from 3 million (I ask on my first visit) and require lots of technical maintenance which is very expensive. The biggest plus for me was being able to have the first appointment each day so I could continue working. Our public system is also excellent with well trained professional experts who often work across both public and private, but most public hospitals are also training hospitals and care for larger numbers of patients and I would expect this makes them viable on the medicare scheduled fee.