OP,
Blokes shouting/ honking horns at women runners is a 'perceived safety' thing for them...the fact they can just amuse their mates, speed off and not face up to an irate/ upset female.
And that they simply don't (bother to try and?) understand how intimidating it can feel to be on the receiving end. Especially cumulatively: theirs could well be the 3rd/ 5th/ 10th... time that's happened to someone on the same flipping run.
(And then there are those delusional few, genuinely believing we'll be impressed by such originality , and we're clearly humourless otherwise. Because it's just a laugh, right?).
Bit like the anonymous cowards trolling from behind a computer screen, I suppose. It's at one remove. They can act like arses and avoid any repercussion.
You could always borrow my damn scary pro-runner friend:
obviously hyper-fit and very speedy, on one legendary occasion she got so incensed by horn-blaring, catcalling idiots, who merrily thought they'd left her far behind, that she shocked the Hell out of them by suddenly hammering on their window, pointing out the error of their ways, and asking in no uncertain terms why they felt the need to make lone runners feel vulnerable...
And, yes, she does realise it wasn't the safest idea, but 25 years of random harassment made her snap.
And it took place in broad daylight, on town centre road, with other drivers and bustling pedestrians around...(many gave her a thumbs-up and a "well done").