If you write 220 tickets and 30 get overturned, you only wrote 190 tickets. Your job is at risk. If you write 210 tickets and only 2 get overturned, you're good!
Not all Black folk are poor, but your probability of getting a ticket that sticks is higher with Black drivers. If you (illegally) search the vehicle and find weed, you might get 2 tickets! The daily double!
But you can't search the car or the person, without escalating. You are *incentivized to escalate*.