What one calls 'tricks' someone else calls preparation. For example standing on a pedestal. If the horse can't do that successfully he might have issues getting into a trailer. If a horse can't tolorate having a ball bounced around he might have the tendency to spook at a big stimulus, say out on the trail. We prepare the horse to be calm in crazy situations and to look to us for guidence and not to freak out.
I recently worked with a horse who would. Not. Get in the trailer, no matter what the owner did. I was her last resort because she needed to get this horse to the trainer's barn....this was also going to be the first time the horse had been hauled, ever. She was skeptical because I do Parelli, but she had no other options. The first day I worked on basic yields (FQ, HQ, back up, come forward), backing over a pole, standing on things, getting the horse to go between me and objects to test how claustrophobic he was....after all the preperation we went to the trailer and after awhile he was loaded. However I wasn't satisfied with his confidence level inside the trailer, so I stopped at a good point and was going to continue the next day. Day two was a very quick refresher, also adding in a bit of circling, and soon he was loading and unloading (which was a huge problem for him) confidently. I then tested our rapport by turning him loose at Liberty to see if he would load for me and he did from 25 ft. Away from the trailer. I told the owner he was ready to haul and he acted like an old pro in the trailer, stood well to be tied and everything. He unloaded beautifully at the trainer's barn. So all those "tricks" and "silly things" paid off BIG TIME....there is something to it if one is willing to look and be open.