Hey Choy, the rail is being built for tourism, not aimed to provide relief for commuter traffic from the west side.  Take a visit to see how the rail has been built in Kapolei.  The end point is clearly targeted to run to Ko'Olina.  So there you have, a rail system that connects Ala Moana Shopping Center, the airport, Pearl Ridge Mall, Kamakana Alii Mall, and eventually Ko'Olina.  Additionally, the state will develop the Aloha Stadium site as another mall/shopping center/commercial development.  So taxing tourism seems to be in order.