[DNSB]

Originally Posted by ApK

Pretty sure they're right on that one. Voluntarism is the system, like most other isms. They're clearly speaking of system and theory, not just the act of individuals volunteering.
https://www.merriam-webster.com/dictionary/voluntarism

The use of voluntarism in the sense of relying on volunteers for support or action is an Americanism which does not really fit into an Australian publication. Using volunteerism would give the same meaning as the article appears to have meant in pretty much any English speaking country. OTOH, given the rather fluid nature of meaning in the English language at the best of times, King Canute ordering the tide back comes to mind.

See the Wikitionary entry on voluntarism or the Dictionary.com comparison.