Think back to the last time you received a delivery from Amazon. Did the driver who handed it to you look happy? That driver was quite possibly subjected to an inhuman work schedule and may have been cheated out of some pay as well. At least, that's how things appear based on interviews with 31 drivers published by Business Insider. These drivers did not work directly for Amazon, but for the many shipping contractors the company hires to handle its logistics. 

One driver described being mocked when he wanted to seek medical attention for a work-related injury without finishing his deliveries first. Others said they were refused overtime pay although they worked well over 40 hours in a week. Some said expected paychecks failed to arrive, or that they were fired right before they reached the 90 days' employment that would let them qualify for health insurance. 

And many said they were expected to adhere to impossible schedules, for instance delivering 200 to 300 packages during a nine-hour shift that was supposed to include a half-hour lunch break and two 15-minute bathroom breaks. Simple math will tell you it can't be done: To deliver even 200 items during eight hours of work (subtracting an hour  for breaks) you would have to deliver a package every 2 minutes and 24 seconds. All day.

Faced with the expectation to meet schedules like these or risk losing their jobs, drivers say they not only skip stopping for lunch, but also for bathroom breaks. Instead, they commonly urinate into bottles or (for women) buckets rather than spend the time to seek out a rest room. They also say the brutal schedule leads to dangerous driving habits such as speeding and running stop signs. One driver said he almost hit a child while trying to keep to his Amazon schedule. He slowed down after that--and fell behind on his deliveries. 

But even using tactics like these, many drivers can't complete their deliveries in a nine-hour shift, they said. (Even with no breaks at all, you'd still need to deliver a package every 2 minutes and 42 seconds to reach 200 in a nine-hour shift.) Instead, they report working extra hours, sometimes as much as 15 or 16 hours in a day.

Asked to respond to these accounts, Amazon's Amanda Ip told Business Insider, "While it is impossible to characterize a network of thousands of delivery drivers based on anecdotes, we do recognize small businesses sometimes need more support when scaling fast." Fair enough: 31 people, some of whom have moved on to other jobs, is not a representative sampling of Amazon's vast array of worldwide delivery drivers.

As to the tight schedules, Ip said, "The majority of drivers complete their daily routes in under nine hours, which factor in breaks, traffic patterns, and more." But she apparently did not confirm or deny that drivers were expected to deliver 200 or more packages per shift, nor did she explain how it might be possible to do that within eight or even nine hours.

Amazon invites drivers to report problems.

To Amazon's credit, it has not sought to disavow responsibility for how its contractors treat their employees. In fact, the company told Business Insider that any driver experiencing mistreatment from a logistics company should report that mistreatment directly to Amazon and has several options for doing so, including using its chat support service. The company said it takes such reports seriously and will investigate any contractor that may not be following its rules about reasonable wages and schedules. And several lawsuits by drivers that named both the contractors they worked for and Amazon have been settled, although Amazon admitted no wrongdoing.

At the heart of the issue is Amazon's Delivery Service Partners program which recruits entrepreneurs to start delivery companies that will transport Amazon products. According to Amazon, entrepreneurs can start up with as little as $10,000, using Amazon-branded vehicles leased on favorable terms. The retailer will even provide training for entrepreneurs joining the program. It's a great way for a new entrepreneur without a lot of capital to start a company, but it's also a great way for those with a questionable past to start over. For instance, one of the logistics companies serving Amazon is headed by a former stockbroker now barred from the securities industry as part of his settlement with the SEC over a fraud case. It perhaps isn't surprising that multiple employees reported this same entrepreneur often did not pay drivers on time.

But the bigger problem is the expectation Amazon has created among customers that they can have anything they want within 48 hours without paying for expedited shipping. More than 100 million people have signed up for Amazon's Prime service which costs $119 a year and provides free two- or one-day shipping on a huge array of items. Customers can use this free shipping as often as they like, and they do. This is why, according to Amazon's financial filings, annual delivery expenses have risen from $1.2 billion to $21.7 billion over the past decade. 

That rising cost is a problem for Amazon, one that the Delivery Service Partners program is intended to solve. Amazon has expressed worry over the power that Federal Express and UPS can wield over it. Having hundreds of small companies whose only customer is Amazon competing to win its favor puts the retailer in the driver's seat. 

That's something the logistics companies are well aware of, drivers and managers told Business Insider. They know that Amazon can reduce or terminate deliveries with them at any time. So when Amazon managers track delivery drivers via their handheld devices and call to ask why a driver has paused during his or her route, that driver's boss will take that question very seriously.

In the end, it's a system that benefits almost everyone. Amazon wins because it can deliver more products at lower cost, becoming more profitable and reducing its dependence on the established shipping giants. Logistics entrepreneurs taking part in the program win because they get to start a business with a minimum investment, and as my colleague Bill Murphy noted, could wind up making a lot of money. And Amazon Prime customers win because we can keep buying products at attractive prices and receiving them in one or two days without having to pay for shipping.

The only losers may be the drivers. Caught between a giant company looking to deliver ever more packages, faster, and at lower cost and an employer who's desperate to please that giant company, most have no option but to keep driving on.