I'd like to understand more about the systems that require pager duty? I don't work for AMZN, but as I understand it the internal infrastructure is highly serv

I'd like to understand more about the systems that require pager duty? I don't work for AMZN, but as I understand it the internal infrastructure is highly service-ified, so (ideally) pager-duty activities are hopefully somewhat contained. And, I would imagine those issues relates to less-mature systems in play. Which leads me to my impression: it's 2015, AMZN has been around for 20 years, and their warehouses weren't just propped up yesterday. If pager duty involves looking into more mature systems interacting with others, then those activities will only get worse over time. It becomes maintenance nightmare land, something you can only do by churning through people. AMZN has some hard engineering problems to solve, but I wouldn't label it a top-notch engineering organization.