Endless Customer Base
Finally, the government cannot choose its customers. Corporations can make very specific decisions to segment their market and only service specific customers. A customer's affluence, demographics, health, taste, or any multitude of factors can be part of the selection criteria of a "good customer." In general, though, governments are supposed to serve everyone. That makes systems extremely complex.
To use terms that systems testers use, there are few edge cases, because the system has to accommodate every condition. "Every" is a very large number. The systems cannot ignore the rich, the poor, and those with means to pay and those without. It cannot omit the healthy or the unhealthy, preexisting conditions, or anyone else.
Some people may not get services, but they still need to be consciously addressed.
While government projects may actually fail at disproportionately higher rates than in the corporate world, that is an unfair comparison. There are too many factors that make them different from or incomparable to corporate projects. To be clear, I have not found data to prove they actually run worse.
As opposed to their corporate brethren, public sector projects run in the light of day, hence, every hiccup, glitch, and misstep is in full public view to be criticized by every armchair "executive." As leaders, our job is to look at the failure reasons and determine how to mitigate the risk in our projects whether they are public or private.