[kintamanimatt]

Some people will be embarrassed to make that phone call. Some people won't be able to do it because they don't have a credit card (if they're on PAYG, for example) and will have to go into a store, which is inconvenient, time consuming, and potentially embarrassing. For others, in the case of a wireline internet connection, the account might not be in their name and they will be unable to do it. I've had situations where the internet connection wasn't under my name but my housemate's name, and, of course, I couldn't have just called up or clicky clickied and disabled the censorship. I'm not someone that embarrasses easily but there are those that might not want to have that conversation with their housemate. What if those housemates decided that they didn't want porn going over the household's internet connection, or were too embarrassed themselves?

The next few generations are going to grow up with the idea that nanny filters and censorship is fine, or that porn is something shameful that you have to ask permission from a CSR to see. Then there's the sophisticated central apparatus in place for the government to trivially block any sites that they deem unsuitable, content they might deem exempt from their opt-out procedures.

Just because O2 and other UK mobile operators have been censoring for a while doesn't make it okay. Now you're arguing that censorship-by-default is fine because it's been going on in some capacity for a while already! See how this works?