Эти - не все. Роулинг людей с мозгами очень не любит, тем паче на переднем плане. А цитата из Дамблдора? Пожалуйста:
"But how come the Ministry didn't realize that Voldemort had done all that to Morfin?" Harry asked angrily "He was underage at the time, wasn't he? I thought they could detect underage magic!"
И ответ Дамблдора:
"You are quite right — they can detect magic, but not the perpetrator: You will remember that you were blamed by the Ministry for the Hover Charm that was, in fact, cast by —"
Совершенно однозначно заявлено, что работает оно не по человеку.