We're a 300-year-old country going through major growing pains.

Nothing about modern America is that old at all, a hundred years ago we may have still had the same form of government, but our ways of life were completely different and our government played a much different role in our lives. All of this is new, like within the last century.

There’s also the possibility that although other regimes were counterfeiting the greenback through the Cold War, Americans weren’t affected (due to the high demand for the greenback) and couldn’t do much about state actors like DPRK anyway. Modern USD notes are far more difficult to copy. Without bulk-counterfeiting or debasement by the Fed, Americans would have the same problems as the Swiss did when the Swiss Franc briefly became a safe haven reserve in the 2010 era.

And as sandworm alludes to down thread, Americans (USG) extended full faith and credit to all notes, whether old new or counterfeit, so that faith in the dollar would never come into doubt.

"Greenbacks" are also part of the national identity. I've seen very few proposed redesigns of the dollar that don't look abysmal. The only one I'd want to both put in my wallet and represent the United States in the hands of people worldwide is the set from Andrey Avgust.

That's true for some things, but not for others. I think good heuristic is the more something interacts with government rules and regulations, the slower it changes.

That’s why the mint is adding one color at a time over decades. The $10s aren’t really green anymore.

Yeah, but it's also the place where most new things and trends come from.

Less now than in decades past, but still to a large degree.