If you want to spend firefighting budget, preventative measures are about as expensive as fighting the fires, and you're still going to get fires anyway. If you are thinking purely in cost of appliances and man-hours, putting crews in the middle of nowhere running controlled burns is pretty costly.

In Australia, cut funding to firefighting caused a reduction in preventative measures, which significantly worsened our 2019/2020 fire season to say the least. An outcome that was signaled to policy makers by the firefighters well in advance of the fires. Pretty much the opposite to the scenario you've described, but in my opinion an outcome that was fairly obvious.