Not all of them. I’m on Zen, no filters as far as I’m aware, sci-hub works fine. Libgen is fine. Torrent sites that the ‘main’ ISPs block come up just fine, too.
The UK government threatened to make it a legal requirement that all internet connections have filters for adult content on by default.
The major ISPs and mobile networks voluntarily put filtering in place by default to avoid the regulation.
The filters can usually be removed quite easily.
While there are some smaller ISPs that don't put filtering in place, they account for something like < 10% of the market.
Yes, you can disable it quite easily. Usually by entering a credit card number in their app or website to prove you're 18, or alternatively by contacting their customer service chat.
But of course, only pervs who want to access porn would do that, right?
In my experience it's a good idea to disable it regardless, it as there are often a lot of "false positives", and the filtering can sometimes cause performance problems. (Unless you've got kids and really do want to block porn, but eventually they're gong to discover VPNs...)
No? Why would you say this? I disabled this back with my old carrier and it was pretty painless - I don't recall there being any stigma attatched to turning off the filters. I've since moved carriers and I don't remember having to disable filters - maybe I did or maybe something about signing up turned it off?
Painless based on provider, otherwise what described above is a pain.
Are people actually afraid of some stranger call-center worker silently judging them, but not even saying anything out-loud about it because the call is recorded and they'd be fired if they tried to actually shame you?
I'm not sure why you would want your ISP interfering with your traffic like this. To me, it seems like a dealbreaker.