Tipping 15%
In most restaurants, tipping 15% isn't enough, yet that's the standard American tipping rate. 20% or over is courteous, and the norm in most other countries, but Americans are notoriously stingy. Think about tacking on the extra 5% next time you go out.
Confusing Money
The monetary system in America is confusing for nearly everybody, but especially for blind people. All the bills feel exactly the same and the coins are too similar in size to be differentiated between easily. In countries like England, their money is all different shapes, sizes, and textures. In most cases, the money will likely become totally virtual in a few years, anyways.