I saw someone bike with their kids to school in a protected (raised) cycle lane. A narcissistic driver came and drove over the curb and parked in it. No easy way to to the sidewalk due to a fence and plants. The kids therefore had to go around the car by biking to down the curb and into the lane with cars and then lift their bikes up again.

Do you think having 6 year olds biking in the middle of traffic is acceptable, just to placate drivers? And it's 100 meters and then it's a new car. And another one. All the time.

I certainly don't give one whit for "placating" drivers. If you have time, take a pic, file a ticket, call the non-emergency police number. Great.

And then the adult can use their bike to take the lane, stopping traffic, and let the 6 year old go around.

No need for loud horns or confronting people.