So most folks don't opt out unless they want to bind themselves against self-control problems, they want to keep the kids out of that stuff, or they want to make a symbolic statement against pornography and in favour of the ISPs that provide filtered service.
Some Brit MPs wish to reverse the default:
The biggest broadband providers, including BT, Virgin Media and TalkTalk, are being called to a meeting next month by Ed Vaizey, the communications minister, and will be asked to change how pornography gets into homes.More wonderful libertarian "nudge" paternalism from the Brits. Those who enjoy the stuff would still get it, but only if they explicitly sign up for it and presumably get put onto some government list of known pornography viewers which will presumably get out via Wikileaks within a few years. Then the journos could have fun looking at the lists of which prominent people have signed up for the uncensored stream and folks can snicker about their neighbours' viewing habits.
Instead of using parental controls to stop access to pornography - so-called "opting out" - the tap will be turned off at source. Adults will then have to "opt in."
Claire Perry, the Tory MP for Devizes and a keen lobbyist for more restrictions, said: "Unless we show leadership, the internet industry is not going to self-regulate. The minister has said he will get the ISPs together and say, 'Either you clean out your stables or we are going to do it for you'."
"There is this very uneasy sense for parents of children that we do not have to tolerate this Wild West approach. We are not coming at this from an anti-porn perspective. We just want to make sure our children aren't stumbling across things we don't want them to see."
The big difference between the two default rules is that the opt out rules allow folks with "deviant" tastes to pool with those who are indifferent, while opt-in only selects those whose preference intensity is strong enough to be happy about being on the list. Nothing is currently signaled by failure to opt out but opting-in would say rather a lot: you're either a consumer of the product, or a very strong civil libertarian.
I'm going to bet that this doesn't wind up being implemented. Here's Hansard of the debate. The Minister seemed pretty lukewarm on pushing through regulatory changes; I'll guess that the latest reports are bargaining position for either getting ISPs to do more to push subsidized Net Nanny variants to folks who want them, or for concessions on other issues altogether. Dick Puddlecote is livid (rightly so) but I'd be shorting the iPredict contract at prices higher than $0.35. It's pretty disgusting that a coalition that includes the Lib Dems would be even making noises in this direction.