Sort of like how per diem and tax returns work? The IRS says you can account for $XX without receipts in our industry as it is "deemed substantiated." So most airline workers deduct their full allowable amount because receipts aren't necessary up to the maximum set by the IRS, but you know full well that most don't spend anywhere close to the limit. No one is doing anything illegal, but the spirit and intent of the IRS rules are certainly not followed.