This is one of those "told you so" moments.
My first trip to the United Sates was in 1984, and that was the first time I has a walletful of this strange green money. And compared to the British banknotes I had used up until that moment, I immediately noticed that you could not tell the notes apart unless you were sighted. Though in recent years newer "bills" have got a bit more colourful, they are still all the same size.
Of course when this arose in converstaion with my new in-laws they looked at me like I was barmy.
Just like the waitress at the Holiday Inn at Charlotte NC. I had asked for marmalade at breakfast and she said "This is America, honey!"