I live in a location where honking the horn is actually written into the law regarding overtaking/passing - it is literally the 1st thing you are mandated to do by law even before using the turn signal.
Fortunately almost no one pays it any attention.
What a time to be alive!
Fun fact - the driver doing the passing has the right-of-way and the vehicle getting passed is obligated to slow down and do whatever else is required for the passing driver to complete their pass.
We have stupid laws here.