LEOs view the initial offense as a lead that gives them probable cause to start fishing for more serious offenses once they initiate the stop. But they're not going to nail a self-driving car for DUI, drugs, weapons, etc.
To a certain degree, all minor traffic stops are pretextual stops. They're an "in" to look for more serious offenses.
One thing I am very curious about, though, is how the system of adding points to a license for certain traffic infractions translates to self-driving cars. Surely it would not make sense to add points on a car-by-car level, since every car in each fleet is presumably running the same software, but applying them to Cruise or Waymo in the aggregate doesn't make sense, either, unless there's some sort of formula for "points per mile driven across the fleet."