While one can definitely argue against this view, it's far from absurd: the basic argument is that the availability of private college/lawyers/your-favourite-resource favours the rich and powerful, and that you can only get actual equal access for all to education/trial-defense/something-else if you force the rich and powerful to have an equal playing field with everyone else (at which point they will then use their power to ensure a decent/good level of the service for everyone, including themselves).
Two fairly different, and likely overly generalised and simplified, examples of this view: - the British left-wing view of private (known as "public" in Britain, to confuse us all) schools (vs state schools): they allow the rich&powerful to get away with underfunding/neglecting the state school system, as it doesn't actually affect them, their family or their friends' family - the Swiss view of public schools - paraphrasable as "Swiss private schools are for foreigners" - which more or less implies that using (or a society needing) a private school is a moral failing ;) (ie the rich&powerful will help fix the public schools rather than send their children to the private one)