&#62; Buses are also generally unpleasant, usually populated by people with vast, on-display, personal problems like drug addiction, homelessness, mental health problems, etc. Mostly because people without these problems have cars and simply drive.<p>Some say car dependent suburbs are in large part a means for the middle class to self segregate from the underclass.  In other words, avoid the people who can't afford to drive everywhere.<p>Arguably, the really good public transportation systems are all in fairly homogeneous societies with little to no social underclass.  This might even hold within the US.  Portland is one of the most homogeneous cities in America and has the densest middle class neighborhoods and decent transit.