If you've ever seen Euros or Australian dollars, they have a lot of accessibility features such as each denomination being a different size and color and raised print. As per usual for the US, somebody had to sue to get anything done and get accessibility considered, the US bills being the only currency out of 180 to have all of its bills be the same size. The lawsuit started in 2006 and the results might be fully rolled out by 2030. At least one redesign since the decision ignored accessibility for the blind.
Australia has fun names for some bills like lobster and pineapple. Extra bonus: no pictures of slave owners like on the US $1 and $2 bills.