Various inventions that have become well-known were never patented, including the karaoke machine, emoticons, matches, and the magnetic strip. Other noteworthy examples include the polio vaccine (invented by Jonas Salk) and monoclonal antibodies (Cesar Milstein).
I am interested in systemic, empirical studies that look into such unpatented inventions in more detail. More specifically, I am curious as to what different factors influenced why certain inventions were not patented. Was it because of certain political ideals of the inventor, not filing on time, the invention being too much akin to other products or inventions, or something else?
Moreover, I would like to learn what social, political, judicial, and economic factors play a part in how unpatented inventions came to be. Any academic analyses describing the political economic background of (un)patented inventions are therefore of interest to me.