MP's Expenses - The Fees Office and evidence

From an Operational Risk point of view, it seems hard to believe that receipts and evidence of expenditure do not have to be submitted for certain items of expenditure. This whole sorry debacle serves to highlight the obvious need for receipts or evidence to be submitted by everyone claiming expenses - but perhaps moreso, is the need for those authorising expense claims to be in a position of authority, able to decline expenses when necessary and request back-up information from any employee, whether senior or junior.