This may very well be an unpopular opinion but I’m going to throw it out there and put on my flame suit.
I’ve had pretty much 100% success with that I call “the patience tree”. A horse that doesn’t respect being tied or just loses his mind when he’s away from this friends is basically tied to a tree and allowed to work through their issues.
To be clear, the horse is always tied on a decent legnth of line where he can put his head down and move around a bit, without it being so long he could put a leg over it, and it’s VITAL the horse be tied with the actual tie as high as possible and absolutely above the height of the withers. It usually takes about 45 minutes (but I’ve known horses to take longer) to realize that 1) they’re tied, that’s the end of it, they can’t break away, and 2) absolutely noting is hurting them or making their lives miserable right now except themselves. Usually they eventually realize this and have a bit of a snooze after a while. I’ve never once had one get hurt in any way, nor have I seen it fail to improve the horse’s tying behavior. I’ve also used it (but much more rarely) with a cross-tie type set up.
Equally importantly is that the horse be left alone. Attempts to comfort the horse while he’s upset about being tied only encourage the beahvior, and it goes without saying the tie up should be firm and unbreakable but have a quick release that you, not the horse, can use if needed. I always make sure the horse has had a nice breakfast and a good drink and if possible some turn out before going to the patience tree to put everything in their favor, and if they’re not getting the idea after a couple hours they get a break where they’re fe, watered, and possibly turned out for a bit, and then it’s back to the patience tree. Horses should never be tied all day, over night, or if there’s not someone in the vicinity keeping has an eye on them. They should absolutely not be deprived of regular water or food throughout the day, or tied out if they’re full of energy which would be better expended in turnout or on a ride, as that’s setting them up for a worse session than necessary.
Also most likely the horse has figured out a great trick that never fails. Don’t want to be on the cross ties? Well just rear and they fall right away! I once working in a barn that had chain cross ties and used nylon halters, with no breakaways in the system at all (which I don’t necessarily condone), and while I saw a couple horses put on a good show of pulling back, the cross ties held them and the horse eventually just settled and realized the whole pulling or rearing this was useless. But again, there’s an amount of risk with that especially if the floor is concrete and they could slip.
I always introduction horses to cross ties by trying one side of the cross tie, and then just firmly wrapping the lead rope to the other wall in a way that mimics the other cross tie but will release under firm pressure. However I do that to avoid them learning to rear or pull, and while it’s safer to do it that way with a rearer it may also not stop the behavior or may possibly encourage it.
I have a horse who will break the cross ties at any opportunity, because he picked up the habit before I got him. However it looks pretty dramatic when he tries, but when he realizes he can’t break free he just kinda gives up on it for the day, and he’s never actually putting a full-body panicked effort into it, just a really good try to see if it’ll work this time.
Behavior which is no longer brings the desired reward after repeated attempts will cease. If it works, even some of the time, it will continue pretty much foever. It also seems to be the case that horses are much less comfortable being tied in aisles with a lot of space behind them than in a more enclosed area.
Again, a lot of people may disagree with what I’ve just said, and it should absolutely not be attempted if you don’t feel confident in your ability to safely tie or if you refuse to tie without a break away. However as I said when done correctly I’ve never seen it not work and never seen a horse get hurt.