Why are White students more likely to be suspended for provable offenses versus
Black students who are more likely to be
suspended for subjective offenses such
as talking back and insubordination?

fear = prejudice = unfair treatment

Explanation:

due to disproportionate rates of crime in black communities, many black kids are unfortunately labeled as being more likely to be untrustworthy and/or violent. This causes a general sense of unease in the prejudiced party, making them more likely to report and punish the black kid for a disproportionate offense.

This is a pattern that can be seen in any marginalized community, and frankly, the colour of one's skin is not the factor at play. This happens to LGBT people, immigrants of any colour, it can happen to any group which is stereotyped as being dangerous in some capacity.

This is where we get into the concept of intersectionality, such as how a black person can oppress a white lgbt person, and so on and so forth. It's all relative to the specific situation at hand.