That is most common, but a tiny minority see no colors.

That just proves one struggles with a lot of not well thought out assignments, not with all of them. That still means a badly designed book.

I grew up, as most of my friends, using a lot of xeroed exercise books and exercises notebooks. Monochrome copies, of course.

Never saw anyone having issues with that, weather 7 or 19 years old. If a kid struggles with monochrome computer screen, it means his learning materials are designed worse than post-soviet era 25 year old textbook.

BTW. I am eagerly waiting for better availability of eink monitors.

also, they're not the same colour to me in bright sunlight - one is light murky brown and the other is dark murky brown. under fluorescent lighting they are both the same shade of murky brown.

Red green does not mean that you ONLY have problem with those 2 colors. Means you will have problems with ANY color which is composed of some of the 2. Also there are Red/Blue Green/Blue... basically any combination. So relying in only colors is just bad design.