David Browne is a classic American archetype - the hobo. Although the hobo "lifestyle" saw its peak during the Great Depression, there were still a large number of these vagabond travelers around in the early 1960's. However, due in large part to the implementation of the welfare system in the mid 1960's and tougher local vagrancy laws, the hobo seemingly vanished from the American landscape by the end of the 60's.
Andy's attitude toward David Browne, general acceptance without actual approval, was fairly common. Although most folks saw petty theft and vagrancy as crimes, hobo's were often tolerated due to the fact that many were simply down on their luck. What makes David Browne interesting is that he clearly chooses the life he lives. He appears to have both the intelligence and the ability to lead a "normal" life, but instead chooses to live the nomadic life - with all of its illusory freedoms.