[wongarsu]

I don't think "vital function" should be the only test applied. For example power plants are extremely vital, but at least around here we have no problem having them privately owned.

A better test would be "vital function and strongly tends to a natural monopoly". That's what we experience with sewers, power lines, roads etc., which is why usually they are operated publicly.

With search that's not so obviously true: Google dominates because they got a big lead at the right time, and now nobody can match them in scale. But that can be solved, for example by giving grants to promising search engines to offset their costs, or by operating a crawler from public funds and giving everyone free access to the crawls (which would be kind of the digital equivalent of operating libraries).