I've said my stuff on this forum about this issue before, and as usual there has been some backlash. We, as vulnerable road users, should know better than to be less than supportive of other vulnerable road users. If you think you are vulnerable on a bike, you can probably multiply this by x10 for a horse rider. Our roads were built for horses. They don't need to tax their horses, like we don't need to tax our bikes. We just need to respect each other, and be respectful and careful around each other. There will unfortunately be twats on bikes who don't, and there will be a few on horseback who don't. But we should be uniting against a common enemy (the motorist as 'king' of the road) and not making things even harder for each other.
I live amongst people who are in both camps, so hear complaints on both sides. People who 15 years ago could ride a traffic-shy horse safely on a bridle way are now having to deal with the 'mountain biker'- some riders of whom don't appear to give a shit. Courtesy to riders from motorised traffic seems to be at an all time low. If you think being close-passed by a HGV with 6" clearance is terrifying on a bike (and believe me, I have been there), you should try that on 500kg of terrified horse who doesnt know they need to hold their breath and not deviate an inch from their line or they and their rider are instant road kill. I hate people sometimes (no matter what their chosen transport mechanism is)
One of my close friends from vet school at uni is minus a kidney after being hit by a twattish motorist. Her horse died. She had done nothing wrong, just like so many of our fallen cyclist friends