No matter how they do verification, the scheme won't have the intended effect as there are massive numbers of non-commercial sites which make porn available, in

No matter how they do verification, the scheme won't have the intended effect as there are massive numbers of non-commercial sites which make porn available, including pretty much any site that allows user generated content. And on the other side we have a load of personal information given to a load more sites on the Internet, with all the potential for problems if/when they get hacked (e.g. Ashley Madison)