I used to repair ATM’s for my bank as a side income. We always worked in pairs to prevent theft. One time we opened a machine and the “extra” cash totaled almost $200,000. That was actually a security breach to have that much money in an ATM, even if it WAS embedded in the bank’s brick wall.
The problem is that even with two people you run the risk of flight or collusion if the incentive is great enough. In our case, we didn’t even think of it. When you deal with that much cash all the time, you don’t even see it as money. Literally.
“The problem is that even with two people you run the risk of flight or collusion if the incentive is great enough.”
I’ve seen companies where they have policies that prevent hiring of relatives in order to prevent collusion; it is a misguided practice (with the exception of spouses, because under US law one can’t be compelled to testify against the other). In the meantime, I see de facto theft by managers hiring their friends for fabricated positions with no responsibilities at all (literally playing solitaire all day, interrupted only by lunch).