Wow, just....wow. If you can't teach a horse to lead or start them under saddle without something like this, then you have no business trying it in the first place. Way too easy to kill both horse and rider in something like that.
And I was thinking, don't you have to be able to lead the horse and have it trust you to even get it in that thing? You have to already have the horse halfway taught what that stupid thing is supposed to teach them.