Actual studies of plea bargaining have shown that there are racial biases in what prosecutors offer in deals between black and white defendants [0]. It seems unlikely that the same bias would not also be reflected in decisions to charge in the first place.
[0] https://www.bja.gov/Publications/PleaBargainingResearchSumma...: "Studies that assess the effects of race find that blacks are less likely to receive a reduced charge compared with whites (Farnworth and Teske, 1995; Johnson, 2003; Kellough and Wortley, 2002; Ulmer and Bradley, 2006). Additionally, one study found that blacks are also less likely to receive the benefits of shorter or reduced sentences as a result of the exercise of prosecutorial discretion during plea bargaining (Johnson, 2003)."
Now, if they had gone and showed that first time offenders, for example, had shown a racial bias between blacks and whites, you'd have me impressed.
In effect, you are going back to the original argument, that it's just systemic racism. Unfortunately, you have not provided any falsifiable evidence that this is true.
My statements are purposely written to be read independent of the context in this thread to avoid your exact rebuttal. Maybe you were expecting someone else to reply to you.
Continuing, there is a saying that "prosecutors can get a jury to convict a ham sandwich", although more applicable in civil asset forfeiture proceedings that happen to involve a jury. They can give incorrect instructions, they can give arbitrary instructions, they can create any number of constraints for the jury to consider, and they also screen jury members out for various reasons such as a potential juror's affinity for jury nullification.
This allows for greater success in their conviction rate, especially in the idea of the complacent juror.
The quote is that a good prosecutor can get a grand jury to indict a ham sandwich. The meaning is entirely different from your interpretation.
Having read enough appeals cases I will maintain what I mentioned about what prosecutors have discretion over.