Paper money redesign

This is a good example of how noticing something simple and asking a basic question about whether something very familiar couldn't be 'done' differently can actually be quite revolutionary. Check it out here: US dollar redesign:
"... people tend to handle and deal with money vertically rather than horizontally. You tend to hold a wallet or purse vertically when searching for notes. The majority of people hand over notes vertically when making purchases. All machines accept notes vertically. Therefore a vertical note makes more sense."
So simple you wonder why no-one thought of it before. Of course, you might know that 'they' did: there is often also a sense that a good idea occurs to a number of people independently because the conditions for 'having' the idea are more present at particular points in time. I 'invented' the supermarket trolley coin-return idea about 5 or so years before they began to appear at British supermarkets. I was just told by one of my managers at the time that it would never work, so didn't take it any further (trusting soul that I was)...