There are varying types of colour blindness. For example, there are the "opia" and the "omaly" types. For r/g and y/b these seem to have different ramifications.

Mostly the "omaly" types can get by without too much fuss since colour differentiation is more muted and the "opia" types affect more of the spectrum and more difficulty differentiating if they can at all.

It's more nuanced than that, but generally speaking it tends to work out that way.