How does the data distinguish between a pretext stop, and a stop for a genuine traffic infraction, like minor speeding or a broken light, that a cop uses their

How does the data distinguish between a pretext stop, and a stop for a genuine traffic infraction, like minor speeding or a broken light, that a cop uses their discretion on and issues only a warning? Naively, forcing cops to apply the law even more strictly and always issue fines for minor violations, is not something we want, is it?