I think the point of this rule is that if someone is caught using something like pentobarbitol, there IS a rule that they are breaking, so the USEF has some cause to ban a person, rather than them being able to say “you can’t ban me, it wasn’t in the rules,” and it turning into a messy and expensive legal battle. It’s got nothing to do with rummaging through my tack trunk at a show.
In that light, I can understand the requirement for drugs to be properly labeled. Frankly that’s laughably easy to get around, but it gives them at least some teeth.
Should they have to do it? No. But people suck.