Laws and regulations won't be made per site. Net neutrality regulation would be effective only if you don't leave in backdoors via exceptions.
Also, Wikipedia, being text-heavy and without obtrusive ads, is not something for which zero-rating provides much relief.
That sounds dangerously like "we have this shiny new law that sounds good in theory so we're going to ignore that it hurts actual people in practice, because the theory sounds nice". I think if the law doesn't work "per site", it should be rethought until it does.
What has, and where? All it takes is a quick trip to T-Mobile's website to see the list of video services they've zero-rated without any regulatory issues at all.