Ask HN: Why don't cities/states create their own ride-sharing platform?

Don't dispatch networks seem a lot like infrastructure? The main barrier doesn't seem to be technology, but network effects, and to a lesser extent, government regulation.

Why don't cities/provinces/states make their own?

Adoption wouldn't be an issue, following government code wouldn't be an issue, would probably bring in quite a bit of revenue.

Are any cities doing this already?