Why just porn? Let's have an opt-in for the whole thing
If we are 'protecting the children' why is it always porn which faces the censor's wrath? Surely ALL content suitable for adults only should be opt-in. Do you like video games which are 18-rated? Sorry, you'll have to opt in if you want to see reviews, clips, etc. Horror, violence, any movie with an 18-rating - opt in or you don't get to see it.
What if a 10-year-old clicks on a trailer for 'The Hunger Games' (rated 12A)? Opt in only! What if the household has kids under 5? Shouldn't parents have to opt in to receive content which isn't suitable for pre-schoolers? Think of the damage those TV shows for 8-year-olds might do to a toddler. Think of the children!
Here's an idea. Assume that the default setting is 'no Internet at all'. Then use an opt-in method for the whole thing. All of it. Give this opt-in a special name, something like, oh I dunno, 'service contract' and pay for this opt-in 'service' month by month using an adult-only payment method - a credit card for example. That person could then take responsibility for the viewing habits of the household, because of course what's suitable for Dad might not be okay for little Jimmy.
What? We do that already? Who knew?
Which of these would the average person most like to take part in: sex, violence, torture, death? And yet the portrayal of which one of these is the only one the opt-in will cover?
It's not really about stopping children viewing content which is not age appropriate is it? It's just porn. Bad old corrupting old porn. Bad old LEGAL old porn (because the illegal stuff is ALREADY blocked). Sorry, if porn is bad and must be kept away from children, then so must all other adult-rated content. Cover it all with an opt-in or cover none of it, but don't just pick on porn because... well, why DO they just pick on porn?