In the US, the government is expressly prohibited from regulating video games sales on the basis of content, per the First Amendment (with an exception existing for pornography). This was the Supreme Court’s ruling in Brown v. Entertainment Merchant’s Association (2011).
And that's the problem. The US Constitution isn't Moses' 10 Commandments chiselled in stone. It can be changed and improved. To quote Jeff Jefferies: "That's why it's called an AMENDMENT!".
The fact that the US government is frozen in amber overall will be the downfall of the US.