My God, people, paint is not like ice cream. The grocery is not going
to add chocolate sauce before you leave, making it a "true"
half-gallon.

Like jeffc said, a can of paint is less than 1 gallon so they can add
colorant! How do you suggest they get all those colors if the can is
full to the top?

If it was in fact a base for tinting, there may be some legitimacy, but it still seems like a lot of room for tinting.

5 ounces is by not a lot of tint.