To begin with, there should be no laws to protect children on the internet. It is the parent's responsibility to make sure the child isn't looking at things they shouldn't. Rather than rely on the government to protect the children on the internet, maybe the parents should implement their own locks.
As a parent I do not believe we need laws to protect children on the Internet. I believe this problem should be controlled by the parents. Parents need to protect their children from people in the real world and on the Internet. This shouldn't be a matter controlled by the government.
There is a rhetoric in the US that if we make a law, the activity stops. This is a misconception. What is needed to adequately protect children on the internet is parents. Just like with adults, the enforcement agency and oversight entity needs to be competent and vigilant enough to ensure that the rules aren't being broken by the child. Children can get around filters. They do it all the time. Testing the limits of authority is something kids do best.
If the existing laws were fully enforced, children would likely have enough online protection. However, enforcement of such laws is sometimes lax due to government mismanagement. In other cases, the complicated and huge nature of the Internet can make skirting or breaking laws all too easy. Children are always at risk online no matter what is done.