> remember, they were pulled over for driving erratically

Maybe. Or they were pulled over for being black, or having tattoos, or being really hot, or because they criticized police brutality on social media, or because the officer needs to hit their arrest quota by the end of the month, or because they're driving an expensive car and the officer thinks they'll have lots of cash they can legally rob via civil asset forfeiture. We have far, far too many examples of all of these happening to say with any certainty that the police officer actually suspects anyone of an actual crime.

By the way, I have called in drivers who were badly impaired before. One kept driving up onto the curb, on the sidewalk and grass (next to a school!), then swerving back nearly into the oncoming lane, then stopping in the middle of the road, etc. Another kept swerving toward the concrete barriers on the highway, and when I passed them, they looked visibly asleep. Both times, the cops didn't care. They didn't send anyone. They sounded annoyed that I was bothering about that crap. The police do not care whether people are driving drunk or not, just like they do not care whether an active shooter is gunning down kids in an elementary school. They don't care if a violent dad with a restraining order has kidnapped his kids and is about to murder them, even when the mom tells them exactly where he has taken them. Their interests are orthogonal to the just enforcement of the law.