I wonder what reason that could be? It doesn't make sense to show inflated costs and clubs have to have their accounts audited.
Edit: The source of the figures I guess aren't from the club.
Interesting that - Bournemouth and Burnley despite amongst the lowest budget are surviving in the Premier but Sunderland 10th in the wage table have failed miserably.
It's possible not to break the bank and succeed in the Premier League by making astute signings and paying reasonable wages.