A public transit system is a more efficient, and far less polluting
, way of moving around the large number of people who live in cities
For the many people who cannot, or choose not to own their own car--arguably the nexus of the most polluting, and nature destroying industries ever conceived to make some people a hell of a lot of money--it is the only way to live their lives.
The Toronto Transit System, known affectionately as the TTC, despite attempts by governments to destroy it, is absolutely indispensable to the life ot Toronto.
Another example of the public sector.