User blog comment:AnitaTotallyRocks/Underaged Users/@comment-5413643-20140806020447/@comment-5558012-20140806023007

The law wasn't meant to prevent those under 13 from creating an account. This is a side effect of the law in that companies decide not to allow them to in order to fulfill the law easier. Some companies could have taken more steps to meet the requirements of the law while allowing account creation for those under 13. However, in my understanding Wikia couldn't have done much anyway because they aren't allowed to collect IP addresses with the update and MediaWiki tracks edits via IP addresses or account names.

I don't know about non-Wikia wikis.