Amazon CEO Jeff Bezos says the method he uses to meet the high expectations of "hundreds of millions of divinely discontent customers around the world" is the same one which has helped the company overcome "billions of dollars' worth of failures": having high standards.

"One thing I love about customers is that they are divinely discontent," Bezos says in Amazon's 20th annual shareholder letter released today. "Their expectations are never static – they go up. It's human nature."

In order to stay ahead of "ever-rising customer expectations," Bezos says the entire company refers back to insisting on high standards, one of the Amazon's 14 leadership principles.

Here is the reason the company says it focuses so heavily on this principle:

Leaders have relentlessly high standards - many people may think these standards are unreasonably high. Leaders are continually raising the bar and drive their teams to deliver high quality products, services and processes. Leaders ensure that defects do not get sent down the line and that problems are fixed so they stay fixed.

In the annual shareholder letter, Bezos makes the point that human evolution revolved around people's high standards and insatiable desire to move forward.

"We didn't ascend from our hunter-gatherer days by being satisfied. People have a voracious appetite for a better way, and yesterday's 'wow' quickly becomes today's 'ordinary'," Bezos says.

People's ability to whip out their smartphones to "read reviews, compare prices from multiple retailers, see whether something's in stock, find out how fast it will ship or be available for pick-up," is one reason Bezos says Amazon constantly works to meet the high standards of those "divinely discontent" customers.

