The typical modern American supermarket stocks 48,000 items, each battling for precious shelf space. How do they get there? Why are they arranged the way they are? In the CNBC Original documentary, “Supermarkets Inc: Inside a $500 Billion Money Machine,” correspondent Tyler Mathisen goes inside the neighborhood supermarket and explores an industry that is using every device in its arsenal to learn as much as it can about you—watching, trailing and analyzing your shopping habits in ways you never imagined.