But you don't need to know braille to learn how the most common bills are marked.

Just like you don't need to know Japanese to count the exact amount of yen bills.

Hackernews is filled with you healthy 20 year olds who do not understand that many will by the age of 30 have reduced vision.

Society is not supposed to be engineered for young single healthy 20 year old males.

Chiming in to complain that a good, working solution to a problem just doesn't happen to solve ALL PROBLEMS is just banality or perhaps pedantry. Unless it was also proposing an alternative that might do better...

Braille on money also doesn't help dyslexic quadrplegics with dysesthesia... Checkmate.

I think that's an extremely ungenerous read here. The thread is about how different size bills and different color bills solve a lot of problems with people who have low vision. Adding braille solves the same problem, but for a subset of people that different sized/color bills solves.

If you have a good, working solution that's widely used worldwide, and someone suggests a worse solution that works for fewer people, it's more than fair to point out that "your solution is worse, less common, and works for fewer people".

Your last sentence is a low effort strawman, I'm not sure why you felt it necessary to include.