Age verification by the provider, in the case of porn, is absolutely a completely moronic idea because it shouldn't happen at the server side, at all.
There should simply be an HTML attribute (or something of the sort) that marks adult content. Blocking can happen on the client side trough parental control software or browser settings.
It would be easier and more efficient from a technical point of view, it would work better and be more accurate and it would preserve privacy for users.