I don’t know anyone working on wildfires in the United States for free. Not saying there is no risk, but they are paid and understand the risks. Some nice neighbors have their own contract fire crews, which are not cheap.

In Australia, "most" rural firefighters are volunteers, but have equipment and training providing by their local Government run rural fireservice (that has fulltime paid administrators).

The population density between Australia and the US is radically different though which changes the dynamic (deserts and marginal land exist in both, but Australia is particularly water challenged with no high mountains, so no major rivers).

I know folks that are volunteer wildfire firefighters in Colorado and in California they were enlisting prisoners and paying them very low wages.

Fun fact, NZ and Australian volunteer rural fire-fighters often fly in to help out with bad fire seasons in California. It's good practice.

this happened with some East Coast settlers moving to California after 1870 or so.. many areas known for fire now were the sites of fine home building with expensive techniques and materials, plus the lower quality homes or whatever. English speaking people apparently did not get the memo?