Riders like Anky, Imke and others have fully composed original Kurs, recored with full orchestras etc. It makes a HUGE difference, and makes some of these "supermarket music" kurs look pretty crap tbh.
Apparently there is more and more trouble with copyright music issues because of crackdowns in music copying. There used to be quite simple ways to get "permission" to used copyrighted music for things like dressage, figure skating etc but I suspect it's got a lot more complicated and narrowed the options. Of course the best plan is to have a full, personal composition but that costs insane money, above what most ordinary mortals can justify, I would think.