I'm european and recently got some new dollars because I was flying to Peru and had to spend a night in U.S.

I remember laughing out loud to U.S. funny-money. It's texture is closer to toilet paper than what I'd expect from the worlds most worshiped currency.

And all the bills look identical, have identical colors (although the latest series finally introduced some variation) and are the same size!

The "same size" has ADA implications for low-vision persons, so it's possible that'll change some time. It has some advantages, though, for places that handle cash to have it all the same size (cash drawers, wallets, vending machines, etc).

Once tipped a guy $11 for telling me an interesting story because I mistook the $10 as a second $1. Baffles me that the US hasn't upgraded.

I have a feeling the next generation of U.S. notes will probably end up as a polymer. A friend of mine worked for a while with the Bureau of Engraving and Printing about a decade ago and said that polymer notes were being tested, but at that time, none could survive the very rigorous durability testing the U.S. uses while the linen paper just barely managed to.

But we're in to second or third generation of polymer notes now and the chemistry has improved to the point where they'll make it through the ringer. However, like this article points out, banknote R&D has many years of work behind each issuance, the new U.S. notes that are just now coming out started development 10-15 years ago and the new ones use a new paper formulation. Bonus, the U.S. gets the benefit of observing the results of field usage for other nation's banknotes before committing to a couple trillion dollars in cash printing (more than any other nation).

Here's a brief video on the evolution of the U.S. Banknote https://www.youtube.com/watch?v=QjLD2B5I9yk

https://www.youtube.com/watch?v=2DaVsmsHq0E

Here's some videos on the type of durability testing from Canada's new bills

https://www.youtube.com/watch?v=8odUVIAXPS8

https://www.youtube.com/watch?v=-lDHLNgtzao

and an example of where they fail the test https://www.youtube.com/watch?v=znfOzuCBpAc

> I'm still utterly shocked the US does not have polymer banknotes.

US banknotes are tougher paper than other non-polymer banknote papers, and their longevity is remarkable. They're tough enough that it's still more economical to print new $1 bills then to switch exclusively to a dollar coin (even assuming everyone used the dollar coin.)