Wage theft goes on all the time, subtley, and because a lot of workers don't know their rights it goes on and on. A good case of this in recent(ish) times here in NZ, not to the same scale like Amazon of course, with a retailer, Smith City.
I think they had maybe 20 stores nationwide, and the sales floor staff we expected to turn up at 8:45am for a "team meeting" before the store opened at 9am. It was not mandatory, be expected, as part of being a "team player". If you did not turn up, then you were slowly pushed out of a job - basically they bullied you into turning up for an unpaid 15 mins of work. Usually, the staff are younger people who do not fully know their rights under employment law.
Until, someone decided to push back - the end result was that the Smiths City had to backpay a lot of money - think about this: let's say a conservative 10 staff per store x 20 stores = 200 people x 1/4 hour = 50 hours per day for a 7 day retail business x years = starts to add up to a considerable chunk of change.
Short changing your staff is a sure fire way to screw your own business on so many levels.