I'm not sure if that's a joke? If you have red/green colorblindness, you wouldn't be able to distinguish yellow either. You'd just see blue and not blue.
I love the possibility of having a red/green colorblind character and having to roll to hopefully pick the right potion when they both health potion and poison in their bag.
I feel like any decent adventurer would develop a system. I hear blind people will fold their paper money a certain way so they can differentiate between the different values...
Sure but it falls apart when an asshole gives them a dollar change instead of a 20 and they fold it as a 20. Any system relies on having trust that the system was done correctly as you can't verify.