Slightly pedantic, but the government actually does have a magic money tree and it's called the Bank of England. It can, and does, create money out of thin air. It would be far more accurate to say 'We have a magic money tree but we have to be careful how we use it'.
@anon_opin You can then take it one step further, arriving at Modern Monetary Theory, by concluding that the only purpose of taxation is to make inflation less regressive.