I let it go, I just like to tell drivers when they ****ed up. Same reason I honk at people that pull out in front of me when I drive. Every wreck I've been in or have almost been in was because of people doing that, so I always watch out for it.

At night I strobe my headlight at max directly into their rearview mirror if they come close to hitting me because they passed too close. I figured a horn would be a good daytime option.