There are three basic types of colorblindness, and two of them -- dichromacy and trichromacy -- break down into three subtypes each. When people say "red-green

There are three basic types of colorblindness, and two of them -- dichromacy and trichromacy -- break down into three subtypes each. When people say "red-green colorblindness" they almost always mean deuteranomalous trichromacy (AKA deuteranomaly, "green weakness"), which is A) by far the most common form of "colorblindness", B) for practical purposes mostly affects the yellowish part of the spectrum and C) is typically so mild that most people who are deuteranomalous could go their whole lives without ever knowing it. The problem is that the average person doesn't ever realize this -- just as you apparently believed that the most common form of colorblindness led to an inability to distinguish red from green -- and so there are a huge number of misconceptions floating around which, as one of those 6% of males who are deuteranomalous, I do my best to clear up whenever possible.