Before the rise of affordable automobiles and subways, many people used trolleys-small trains on rails that ran along ordinary streets-to get around in urban areas.
On trolleys, there is a literal "free rider problem":
Since the trains were right next to sidewalks, and since trolleys were wide open and never had doors, people could hop on and off very easily.
How much money will a trolley lose if it is easy to ride for free? If "free riders" are a big problem, what will happen to the supply of trolley rides?
What are a few things the trolley industry could do to solve the problem of free riders?
