Perhaps it seems more prestigious to send your horse off to training camp or bring in a well-known trainer (or perhaps even to have a problem horse??)
I've wondered about this phenomenon a lot. Here's why I think it happens with some people.
First, I think some people don't think they've had a success until the horse is offering the desired behavior. They don't understand the thing Mark Rashid calls "getting to the try." Your friend sounds like one of these - you understood that getting feet on the ramp was a big success, but all your friend saw was a horse who still wouldn't trailer.
I also think some people just have a rotten sense of timing. You know how it's really important to reward the instant
the horse gives you a try? But I've seen lots of people who, through bad timing, will wind up correcting the try - horse does something undesirable, but then realizes its handler disapproves and corrects itself. But by the time the handler's reflexes kick in, the person is correcting at the time of the try, not at the time of the undesired behavior. The horse, naturally, doesn't continue to offer the try.
Then the person starts thinking the animal's just being defiant, forgetting the cardinal rule that "Wrong is not bad, it is just wrong." Person gets frustrated, critter gets frustrated, and nothing good happens after that.
And some people just don't realize what it takes to communicate without a common language. At dog training workshops, we used to play a game where one person tries to get another to accomplish some behavior without telling the person what the behavior is. The "trainer" can only reward efforts in the right direction by blowing a whistle. It's an humbling experience to be the one trying to figure out what is wanted, given such scanty clues!
Also I think you might be right that some people, subconsciously or not, do enjoy having a "problem animal." Never quite figured this one out, but I've sure seen people who were rewarding exactly the behavior they claimed not to want.