You are entirely ignoring the point:
(THEN) the law should treat violators EXACTLY THE SAME
Given that the law is absolutely silent on racial differences, that means the law does not distinguish racial differences and that means the racial animus is NOT SYSTEMIC, it is individual. Those who break the law, even by their interpretation of it, ought to be prosecuted for it. That we do not is just further evidence of individual cause, because the law has no mention of relaxing punishment. That is so bloody obvious, it ought to hit you over the head. That is does not ought to also indicate who has the problem of knowing the difference. Hint: it isn 't the law. What do you think "system": means, after all? Nothing is a system that does not have a consistency to its rules. How people approach and practice those rules is the variation, the disparity you see. If the law did stipulate racial discrimination, then you have systemic racism. It once did, but that time has passed. Some people just don't get it, yet. Got a mirror?