Here’s a thought for you: allowing functionally-blind people (I recently read a novel about a completely blind/deaf/mute ex-cop) with poor touch (calloused or damaged fingertips?) and/or with worn bills to identify bills. I know Euros are different sizes, and I don’t know about UK bills, but US bills are all the same size. Perhaps an app to help blind people be more certain that they haven’t been handed a fake, or handed a lower denomination than they were told. You probably wouldn’t need to include voice or morse-code-vibrate capability; there should be apps which handle that already.
With the computer revolution, most clerks (except in banks) no longer count money out loud by denomination; they just silently drag out a wad of bills, causally riffle though it to be sure it’s in the ballpark (why do you say I sound cynical??), and give it to the customer.
Yes, I know plastic is probably a better overall solution for a blind person…
–Scott, who is hoping his eyes will never get that bad.