lol. I agree. And white Americans who owned black slaves were just employing social bias.
There's a key distinction, there has to be the mindset of "Race A is superior to Race B" in order for something to be racist by definition, the statements of that time period of slavery would be overtly racist.
For instance, the VP of the Confederacy (Alexander Stephens) in his "Cornerstone Speech" said:
Our new government['s]...foundations are laid, its cornerstone rests upon the great truth, that the negro is not equal to the white man; that slavery—subordination to the superior race—is his natural and normal condition.
Even the statements of people at the time opposing slavery were racist
Lincoln made the statement:
I am not, nor ever have been, in favor of bringing about in any way the social and political equality of the white and black races ... I am not nor ever have been in favor of making voters or jurors of Negroes, nor of qualifying them to hold office, nor to intermarry with white people; and I will say in addition to this that there is a physical difference between the white and black races which I believe will forever forbid the two races from living together on terms of social and political equality. And inasmuch as they cannot so live, while they do remain together there must be a position of superior and inferior, and I as much as any other man am in favor of having the superior position assigned to the white race.
Whereas, a judge can say "Being a poor Black teen in the US is an uphill battle, so I'm going to go light on the sentencing"...that's not the judge saying "Black people are superior to White people".
While it can still lead to some disparate sentencing decisions (which are still a problem worth discussing in the context of equality under the law), it's not "racist" by definition, as it's not coming from a place of perceived racial superiority.
That's why we have to adhere to definitions and choose words carefully.
That is, in my opinion, the problem with lumping in racially motivated decisions and other social biases under the umbrella of "racism". The intent is far different in most cases.
For the record, I don't agree with the judge's decision in this case. If people gang up on a person 3 on 1 and give them a concussion, they should receive the full consequences of those actions. But I don't see anything that suggests that this judge made that decision based on a sentiment that "black people are better than white people"