On a day where there is actually high fire risk (ie. high wind in hot weather) this system will be too late and not deliver enough retardant to make any difference. In those conditions you will have tens or hundreds of square meters of fire in within that time. Actual fire ignition will usually not be in the open away from other materials as shown in the example. It may be able to stop fires on days when conditions are mild enough to let it run for the ecosystem benefits.
Not sure that was proved at all - at least where I live, demand was almost certainly propped up by significant numbers of cashed up people in the prime of their working life selling up overseas and buying property when moving home. borders would need to be closed for longer to allow that affect to work out before you could truly see how it would be without immigration.