Think of all of the things we are not preparing for.

Isn't California due for the big one. Should we be spending now to get everyone out before it hits.

Get everyone out? No.

Prepare? Absolutely. I can't speak to the state of California's earthquake preparedness, but there should absolutely be supplies and equipment stationed throughout the state in preparation for it. It is my understanding that San Francisco, for example, has water cisterns throughout the city for fighting fires in such a scenario.

It is dumb not to prepare for disasters we know will happen.

California absolutely can and should prepare for the eventuality of a large earthquake in the area (and they are, as another replier pointed out). Permanently evacuating the whole area maybe not.

Why is disaster preparedness at all controversial?

It wasn't at all clear in advance that all of those things were going to be needed. Mass PCR testing is not part of the standard pandemic response. Neither is the amount and kind of PPE used in this pandemic. I know the UK, for example, had trouble with there being no full-body disposable suits in the pandemic stockpile because they're not usually used for one. Whilst all half-competent countries have systems in place to PCR test, trace, and isolate, they're aimed at high-death-rate diseases like SARS which can't spread undetected because the infected rapidly start showing up at hospitals and which need to be immediately contained once they do. None of this is part of the normal response to a respiratory infection with infectivity and death rate in the same ballpark as a flu pandemic.

"We didn't need it during SARS" is not the right thought process. "What would we need to combat a 1918 style pandemic if it happened today?" is.

That's the whole point. The thought process "what would we need to combat a 1918 style pandemic if it happened today" does not in fact lead to stocking up on the things you're suggesting every country should have because they're supposedly required for any pandemic, since in reality those things weren't part of the plan for a 1918 style pandemic. If the political landscape was different it's entirely possible that (for example) mass PCR testing wouldn't be part of the plan for this pandemic. Most Western countries have the ability to use it for surveillance and estimation of disease spread during a pandemic, but trying to test everyone and use that to stop the spread is not a normal part of the plan for a disease like this.