The number of people saying "It's the law" as if that has any intrinsic meaning is a little astonishing.

Also, from COPPA: While children under 13 can legally give out personal information with their parents' permission, many websites altogether disallow underage children from using their services due to the amount of work involved.

So it's not merely a governmental problem. It's a problem with how much work companies are willing to put in to let children access their services.