Because it was an official response to another MP. Getting it right is the most basic thing any public official has to do. If we can't trust them to proofread things that go out with their name underneath on even the most cursory level, how can we trust that the consideration they have given to the wording in Acts of Parliament is careful and reasoned?

No, it's because we're a bunch of self-righteous nerds. Come on, this is on the level of a simple misspelling. But of course we love correcting people for those too.

Do you think policy-makers should have knowledge about the things they make policy regarding?