Is Sandra's arrest racism? It depends. African Americans are usually lower income and can't necessarily pursue a lawyer to mitigate citations with the prosecutor. 

However, racism will clearly be a claim if there are a disproportionate number of African Americans that make payment to or come before the court on a regular basis. I would not expect citation numbers of African Americans be different to the demographics of the region.

African Americans aren't necessarily going to have bail either which creates greater income in the long run when fines are stacked on top of fines for non-payment or otherwise. 

If a person is issued a warning for a minor violation in the law it begins a recorded history that is an investment over time. The next time that person is stopped there won't be a warning anymore. The foundation to financial exploitation of people begins in a compassionate and logical manner. 

"Don't give 'em a reason." 

The practice of law to the letter is abusive and promotes exploitation. He isn't applying good practice, he practices victimization. 

It is the way I see it and it might be far more systemic than just this instance.