Publicly funded healthcare does not work the way you think it does. There is a budget allocated to healthcare every year, if one year the hospitals don't have enough money to cover expenses but that there is still money left in the coffers (for example, due to less electives), then they will end up getting the money they need to operate.

Were it not for for-profit healthcare, the US would almost certainly operate this way.

There are probably 170 different versions of public systems. I think you're making the mistake of assuming they all operate the same way.

In both public systems I've been a part of, yes there is a hospital budget, but it's paid out through procedures. Don't have anyone in the hospital? No payment.

Sure, but what I'm telling you is that in the event of a major event that means that the amount of procedures goes down drastically which means the healthcare budget is not depleted, but that hospitals need to money to deal with a pandemic, the state steps in and will fund the hospitals.