Elize, I can go to a Hunter/Jumper barn and see just as much lack of education in the riders and their horses as you did at this dressage show, if not more.
And, since you jump, you should be disciplining yourself and your horse in the sport of dressage to obtain the important fundamentals to make yourself and your horse that much better to compeate.
If GP Jumpers spend up to 5 days a week riding and training Dressage, there's a good reason behind it. Most GP horses can do minimally level 3 dressage movements.
I am gobsmacked at the lack of education in Dressage riders have today. Coaches now a days implimenting it in their lessons, or in their students, very sad.
LOL I don't jump, sorry I know I said everything else but I guess I forgot jumping.
Every great dream begins with a dreamer. Always remember, you have within you the strength, the patience, and the passion to reach for the stars to change the world. ~Harriet Tubman