Why do most programming languages only have binary equality comparison operators?

Question

In natural languages, we would say \"some color is a primary color if the color is red, blue, or yellow.\"

In every programming language I\'ve seen, that translates

Answer 1

In python you can do something like this:

color = "green"

if color in ["red", "green", "blue"]:
    print 'Yay'

It is called in operator, which tests for set membership.