I think if we were to open up mail boxes to private delivery companies we'd see lots of small businesses emerge.
Healthcare is an example of privately owned business that has had the essential ingredient of competition lessoned by government and, primarily by unions and business.
About 85% of my healthcare was paid for in my benefit package. I knew that that wouldn't be the case when I retired so I began looking at catastrophic plans that would reduce premiums. I found one that looked good and did a comparison between it and its greatly reduced premium and the Cadillac policy I had. When I looked at what my average out of pocket expenses would be versus the 85% paid premium the policy would have cost me a chunk of money. Others made the same evaluation because when it was time to retire the policy wasn't available anymore.
Capitalism doesn't work where it doesn't exist, where competition is inhibited.