We are no longer that nation. We are far more politically, culturally, and economically balkanized. Huge chunks of our population are cynical to the point of social self harm (this is what leads to all the conspiracies and other nonsense). Its hard to get everyone on the same page when people have embraced ruthless partisanship as a part of their personal identities.
But there are other factors at play, too. That America was much more agrarian. There were many more small and local businesses that were easier to manage as opposed to sprawling corproations.Far more people controlled their day to day lives than in this rancid gig economy we allowed to happen. Things were, in terms of both personal and national commerce and business, substantially less complex than they are now.
And that's not even factoring in the fact that fighting a war, even the largest ever, comes with material and tangible goals that fighting a virus doesn't. Going to work in a factory in America during WW2 didn't come with inherent risks just by going to work. It does now.