I like your idea. I’ve always wondered why they continue to be reactive instead of proactive when we all know the fires come every year. Installing tanks on the ridges ahead of development would no doubt be cheaper than what is happening now. The tanks would have to be there anyway when subdivisions are built. Using them as a preventative measure first does make sense.
until there is an earthquake, and the tank busts open and washes a few hunderd homes and people away...
Because nobody does anything -- especially things that threaten large tax increases -- until they absolutely have to. Why doesn't New Orleans build secure levees? Why do people living in flood or hurricane-prone areas rebuild houses in the very same places after they've been destroyed? Why do people live in trailer homes in twister country? (OK, that last one was to see if you were paying attention).
The truth is most people figure that in the worst case, Uncle Sugar will be there to bail them out. And, judging from recent history, he will be.