Australian public hospitals have first class surgeons. In this case they recommended surgery. They're not doing it for financial gain, why not trust their advice?
Your alternative is to go to another surgeon for a second opinion but you can only do that in the private health system, and that will take months or maybe longer and cost you alot of money.
Also, because people heal naturally at a variable rate. Not every tear or break needs invasive treatment.
Obviously I don't know what happened there, but as an example having a broken bone in their hand which is badly set would fit. It would cause you to have "pain in your hand" and it would require immediate surgery to avoid further damage.
Wife said “no no no I’m not a citizen” and they said “yeah we’re so sorry about the cost” and she laughed.
Counting premiums, we paid $48k out-of-pocket for healthcare here in the US last year.