In our state it is a law to stop when the bus has stop lights on. You can get ticketed for it.
We do not live in a busy area but when my daughter was in elementary school, we did have some issues with people in the neighborhood not stopping and not stopping at stop signs.
We did not call the police. The bus driver has contact with authorities. Afer the bus driver notified the police and told them the specific areas of concern, a police car started hanging out in that area and the city made some some $$ for a little while.
After that, the police would randomly be in the area watching and it stopped because no one knew when the officers were watching.
The law here is very tough in school zones and regarding buses. If the bus driver had not told us that he notified the police, one of us at the bus stop would have.
So, yes. If I were you, I would have notified the police as well because who knows who's child you may be protecting. Since school is almost out... I would be on high alert when school starts in the fall and possibly give the officers a heads up about that time.
Around here a lot of $$ is made for the city when school starts because people forget about the school zones which runs about $200 fine plus if you are on a cell phone that starts at $200 fine as well.