Almost all public utilities have started as private companies of some kind. Broadcast, telecom and railway companies are the most recent examples. They started as private companies but then, due to limited spectrum, unification pressure, needing to include everyone including remote places and wasteful duplication got transformed into publically owned or at least publically licensed and regulated utilities (depending on which utility and country you are looking at).

So, while they are not yet public utilities, they should be turned into such.