The point is that cash differences in a supermarket get noticed within hours. Some level of error can be accepted, but if somebody comes up $40 short several days each week, they're going to be looking for a new job. Mt. Gox claims they didn't know they were being drained of assets for months.
Exactly. I have a friend who while high school in the '60s worked in one of those highway restaurants, if you travel in the right parts of the US you'd remember their name.
Of all their cashiers she had the highest "volatility", you might say, from day to day. That conceptually annoyed her superiors, but they loved her because she never made a big mistake, and her daily errors averaged out very nicely.
