Obviously the truth is somewhere in between, there is no engineer so talented that they can produce a 100% reliable and available system, and the percentage goe

Obviously the truth is somewhere in between, there is no engineer so talented that they can produce a 100% reliable and available system, and the percentage goes down the more complex the system gets. The decision of whether to have a on-call rotation should be based on the consequences of downtime, not on some kind of moral stance on human fallibility.