I was not aware that the was the guide line for IF, but after reading your message and Kavita's I became aware of this. However, I can lie and say I am 50 and can be a 10 year old. I fully understand your point about why the guide line there if its not followed, may be that guide line should be removed, but again in the end its the parent's responsibility to monitor what their children are surfing.
Zee, I think these guidelines are more of statutory requirements in every site to avoid litigation. As you rightly said, in the absence of age proof, it can be faked, but once the site has this specified, it means they have already warned the wannabe member of the age requirement and the members has registered being fully aware of the significance of the statement on the age, but after that it really is not the sites responsibility. That is why parental guidance to net/channel surfing is necessary.
A saying is most applicable here :
You can take a horse to water you cannot force it to drink water.