I live in an area with lots of horses (wild and ridden horses) and lots of recreational cyclists.
The attitude towards horses is completely different and they are typically given much more respect (although the wild horses do have a few casualties each year, pretty much always occurring in the dark of night)
People will pass me on blind bends, into oncoming cars, pass way too close etc,. but as soon as they see a horse they slow right down, pass it widely etc,.
Something more imposing about a horse though I suppose...