Trees are considered shelter in Tx (but I don't know about all states) As for the feet. It "could" be considered cruelty, but if that is "all" then the authorities won't do anything about it.
The draft isn't refusing because it "knows" it is too young. It is refusing because it doesn't know what is wanted from it. Being so young, they have "younger minds" and don't always understand what you (or the so called trainer) is asking it to do.
As stated before, ignorance is not necessairly cruelty, but I do feel bad for those poor horses. What will happen is that they will ruin the horse and then go on to the next one.
BTW most drafts (or at least the many that I have trained) are usually too lazy to buck. They will refuse way before they would buck. IMO if you're too afraid to fall off a horse, you have no business "training" it. (I am not afraid because I do it right by waiting until they are old enough, and lots and lots of ground work. THAT'S the way you don't get bucked off.)
I am afraid that they probably won't listen to you, and there won't be anything you can do about it. Very frustrating, I know.