In almost 50 years I have built in all of those market segments, Government does build a little on its own in public works but for the most part they have their work built by private companies just like Walmart does.
They have their own set of rules and environment just like any very large customer does but they are better than they used to be three decades ago.
Owner’s that build for themselves and long term ownership generally design and then build with that term of ownership in mind — higher quality.
There are many reasons why the free market products are generally superior in cost, quality, and turnaround time than what government produces.
One reason is you’re much more careful what you do with your assets and your money than what you do with someone else’s assets and money. A free enterprise is careful how is spends its own money and uses its own assets. No one in government owns any of the assets government uses and government doesn’t earn it’s money, it forces money from other people. So there’s little incentive in government to maximize quality, minimize coat, and turnaround time. That is why haphazard quality, high cost, and long turnaround time is a generally accurate description of how government works when it ventures beyond what government should really be doing which is mainly protecting the freedom of its citizens.
The Post Office is an obvious example. Nobody owns the post office building and that is why they’re generally run down and dilapidated. The DMV doesn’t care how long you wait and doesn’t care if you’re satisfied with their service once you do get waited on. That’s government. No accountability.
If Walmart subcontracts schlock then at some point Walmart will pay the price and will be out-competed by someone else who pays better attention. In the free market if you fail, you lose and if you don’t fix it, you’re out. In government if you fail, you get more money and a bigger bureaucracy. No reason or accountability.