Most people using Phoenix's new light rail system are using it to get around, not simply for commuting.
Too much thinking on transportation policy in recent decades has been based on premises that "everyone" has a car, highways are crowded at commuting times, and getting people to drive 10 minutes to a train station is a way of relieving highway congestion. In this, even the purpose of mass transit is to aid highway drivers.
Not enough though has been given to improving transit in denser areas where car ownership is optional and people use mass transit for getting around generally. So, non-peak service tends to be reduced, emphasis is placed on bringing people into the central business district, etc.