The issue is that dark patterns are a function of the designer's intent, not the pattern itself. Pre-check a box because you think most of your users prefer it checked? OK. Pre-check a box because you think most of your users don't want it checked and will forget to uncheck it? Dark pattern.

FWIW, intent is fine as a legal criteria. We rely on it to distinguish fraud from honest mistakes. But intent is hard to prove (although not impossible, especially in this age of email and chat).