Obvious regionalist bigotry on your part. What happened when three white idiots in pickup trucks ran down a black man and shot him to death? White prosecutors, a white judge, and eleven white members of the jury convicted them of murder and gave them life sentences without parole. The federal prosecutors and a jury convicted them of federal crimes and sentencing come late this month. This isn’t 1920. Things are done about it.
Note that there were mass protests over the course of several months all over the country and a great deal of media attention surrounding Ahmaud Arbery's murder. The grand jury indictment didn't occur until June of 2020, right in the thick of mass protests that engulfed the nation.
Arbery's killers (and one of George Floyd's) were not prosecuted to the extent they were because our justice system has evolved. It took mass civil disobedience to get even that. Only recently one of Breonna Taylor's killers plead guilty, the first to actually face justice.