To be clear, it's not a sticker to say you can or cannot ram into said car. It's for when you notice an idiot driving 10 mph under the speed limit and before you tailgate them, you see understand the parents are struggling to hold it together and you give them some slack.
It'll barely make a dent as they've literally been screamed at for the last 20 minutes. Might not even hear it depending on what kinda lungs the kids got.
And accidents are increased in increased traffic, passing on the right (or left if you are in a dumb country), large speed deltas from the prevalent flow, and road rage situations. Honking is working as intended and saving lives.
Move the fuck over if you aren't passing or it gets the horn again.