There are so many people who get away with allowing super long feet like that, it seems like most humane societies only care that the equines are getting feed and water. I think lots of huane societies aren't set up or very well educated in larger livestock and they try to avoid having to deal with larger livestock unfortunately. It is changing but not fast enough.

"It's really quite amazing what a horse will do for you, if he only understands what you want. 
And it it's also quite amazing what a horse will do to you if he doesn't." ~ Bill Dorrance