My understanding is that the anti-fraud vacation thing is related to being able to correlate a decrease in fraud with a specific person going on vacation. If you have money that mysteriously goes missing on the regular and 10 employees who touch it along the way, it's hard to determine which of those employees is responsible. If one of them goes away on vacation for a week and no money goes missing that entire week, you suddenly have a much better idea who might have been involved.