There are some objective criteria that can be applied (don't have addons like trip insurance selected by default), but other things are more subjective than this.
Is legislation going to make this better without having unintended consequences that make life difficult for startups who aren't necessarily trying to be sneaky (the quoted language refers to things that are either intended to produce a certain result or have the effect of doing so — even if there was no intention).
I would also note that dark patterns even exist in the legal/governmental sphere. For example, the California Bar website, which lawyers use to pay their annual dues, has optional fees added on by default, and they obscure this fact by making it seem like the default is the barebones cost. It was only after a year or two of paying my fees that I realized how they had hidden these tacked-on fees.
Perhaps the testing ground for anti-dark patterns laws can be governmental websites like calbar.ca.gov!