I think you are thinking of the state of US mobile industry and it's data plans. I'm not aware of any large ISP that has throttles or bandwidth caps (comcast has a supposed 300GB cap but has never to this day enforced it).
> In any case, they only regulate that the porn filter and content filters must be an option
You're forgetting that it's by default on, and that one must call their ISP and "opt-in" to seeing porn. Social stigma aside, how can you realistically and with 100% accuracy block only true porn websites? You cannot, and the UK has shown that over and over as legitimate websites get blocked, including news websites that run stories that relate to porn, etc. The same is true if the filters were expanded to say download websites. And who's to say a website is illegal or not - I for one certainly don't want my government telling me some download sites are legal and others are not.
Not to mention who's to say I intend to break the law simply by visiting a website? Maybe I'm doing research (Brian Krebs), etc.
The very notion of filtering some content goes completely against what net neutrality means.