Half of those examples need to be sustained by the government to actually act as barriers. And all of them ignore the creativity of the entrepreneurial mind whe

Half of those examples need to be sustained by the government to actually act as barriers. And all of them ignore the creativity of the entrepreneurial mind when incentivized by the fabulous profits to be had in a monopolized market. A nice example: https://en.wikipedia.org/wiki/Herbert_Henry_Dow https://en.wikipedia.org/wiki/Herbert_Henry_Dow