The fixture list is the property of the league and of the teams in the league. It's not your property and it is copyrighted, so you can't legally make money from it. That's the rules.
Yes it's not fair really on small, unofficial supporter websites, but it's perfectly fair to generate revenue for the smaller league clubs by making big international news agencies pay for the privilage. Think about the other side of the coin.
Mind you... each league team can designate, if it chooses to, one unofficial site that is permitted to publish the fixture list, in addition to the listing on their own official site. Tranmere Rovers has designated no unofficial site, as far as I'm aware.