The use of Euros vs. dollars is easy to understand. A million dollars in $100 bills weighs 22 pounds. The same value in 500 Euro notes is roughly 3.5 pounds – a lot smaller volume. The US stopped making 500, 1000 and 10000 dollar denomonations just to make it harder on drug dealers. Plus the europeans are not trying to confiscate every “illegally” earned euro like the americans.