Reading this article I just realized how much money large companies like Amazon must make off the interest from the money they've held until payday.
If they pay their workers every two weeks, then they've got a massive pile of cash sitting there waiting (on average) a week before being paid out. Now, a week's worth of interest isn't much to you or me, maybe, but multiplied by the number of workers they are paying it suddenly becomes quite a bit.
Why is it that if I work on a Monday, but you don't pay me until two weeks later, why do you get to hold the interest?