Finally the department has updated the wordings to make it clear that public school contribution is voluntary.
https://education.nsw.gov.au/policy-library/policies/pd-2005…
For years we were confused if school contribution is optional. Other fees are very clear, such as P&C donation (clearly optional), library fund (under gifts section, so again optional), subject contribution (fair enough if you study something that requires extra support materials).
But "school contribution" sounds very vague. If we are voluntarily contributing, then it is just that, shouldn't make it look like paying a bill.
You were unsure if the voluntary contribution was compulsory ?
Nevertheless, I’d urge you to pay it.