One major difference in copyright laws between the US and the UK is the scope of copyright on works created by government employees. In the US, nearly every government work enters the public domain by default, while in the UK all government works are protected under "crown copyright" for 50 years.
But what's the rationale for having a copyright on the state's works? Didn't the taxpayers already pay for it through their taxes? I'm mostly interested in the UK government's official position on this question.