The thing is that much of what happens with a horse that has an inexperienced owner is simply because of that fact. Owner hasn't got a clue.
Owner babies horse, owner uses soothing voice to talk, owner doesn't understand that horse's body language is saying, owner lets horse get by with things, owner doesn't make sure they are the leader.
I have had kid safe horses that I knew for a fact would not ever hurt anyone, turn into raging monsters because of the humans. Too much treat feeding, too much ignoring what was happening.
When you can't get a horse to come out of field? But I can walk up and have no problem? It is you. Not the horse.
Horses and ponies know when a human doesn't know what they are doing.
So the expectation that a horse will behave exactly as it does for an experienced horse person is the worst one that I see.
The second is that horse sellers are going to be totally honest when selling a horse.
Horses make me a better person.