In my experience, public highschools are better about this. In highschool, I saved a lot of time by studying on my own and testing out of courses. It was great.
"Computer science is no more about computers than astronomy is about telescopes."
Maybe they have and maybe they haven't --- it hasn't been proven --- unlike those who completed the first 2 years with a passing grade.
Bottom line --- you and I don't make the rules --- the colleges/universities do. If you want what they got, you play by their rules.
Students with significant previous knowledge and/or self-motivation can just join a regular CS program and take the exams early if they have the prerequisite knowledge, so they won't lose a lot of time.
They don't need to learn everything from the first two years of CS.
And they are free to continue learning on their own the last 2 years of CS.
If you want a degree in CS, you have to earn it --- under the rules of those who can endow you with one.
Does this seem unfair to you?
Most American universities allow precocious high schoolers to graduate in three years, but unless tuition money is a concern, a fourth year to soak it all in is worth it. Your working life is long -- one year is nothing.