What I don't understand about Medium is that it pays non paying members on articles read by its paying members, but these same people do not have effect on reading paying members articles.

I cannot see the logic in this.

Get the Medium app

A button that says 'Download on the App Store', and if clicked it will lead you to the iOS App store
A button that says 'Get it on, Google Play', and if clicked it will lead you to the Google Play store