I live in Mennonite country, and given the callous driving I see every day, it's a wonder that more buggy riders don't die.
Many, many people drive carelessly around horse-drawn buggies. There is simply no excuse for it. Part of the problem could be in a lack of public education.
When I went to driving school, I was taught that you pass a horse-drawn buggy you must give them wide berth, and only return to the right lane when you can see the entire buggy in your rearview mirror. I rarely see anyone else doing that these days. If there is oncoming traffic you just have to slow down and hang back. It's monstrous that many people seem to value a minute or two of their time more than the lives of other people.