(A pispective is when you write about something using only 314 words. Which doesn't include these words or the credit at the bottom).
The private sector is a recent term, coined after the end of the Second World War. It was preceded by 'private enterprise' in the late 18th Century. And about a century before that came 'private property'.
The basic meaning of the word 'private' means not shared. What was private belonged to oneself. 'Privacy' is a little different. It originally meant being secluded, as in removing from public view, or, more simply, being secret. It took on its modern sense of being free from intrusion in the mid 19th Century.
Something that is secret and not shared is the basis of modern competitive advantage. Competitive advantage is information advantage. Advantage from information, in traditional business thinking, comes when the information is secret and not shared. When we talk of "the market" we are referring to the market for information.
Most MBA's are taught the fundamentals of game theory and the power of information asymmetry. Having access to information that you do not gives me an advantage.
But is the private sector private because of its attitudes to keeping information secret and unshared? No. The public sector has similar attitudes. Public agencies compete for funding largely on the basis of how well they leverage their own information advantage. Furthermore, the open data movement came from the private sector.
So, in terms of organizational attitudes to information, is the private and public sectors a meaningful distinction anymore? I think not. The meaningful distinction is how far down the open data spectrum an organization is willing to go.
We are used to the 'public sector' negotiating to share citizen data. What we are less used to are the same negotiations occurring within a single public agency. Yet this happens all the time. And this internal negotiation for information may be less widespread in the 'private sector'.
The idea of 'private' in the context of organizations just means secret.