Why variations accumulate unnoticed
Individually every extra is reasonable. A room needed after an event, an additional attendance during a busy week, a spill cleaned outside the schedule, a store tidied before an inspection. Each is small enough that requesting it formally would seem excessive, so it is asked for verbally by whoever happened to be there, and it appears on an invoice weeks later. By then it has usually been approved verbally by someone who had no idea it was the twelfth.
The problem is not the extras but the absence of a record. Nobody can tell later whether an item was requested, by whom, or whether it was a one-off or has quietly become part of the routine. By the time someone reviews the year, the arrangement has drifted and the original scope no longer describes what is being delivered or paid for. Reconstructing a year of informal requests is close to impossible once the people involved have moved on.
