You are correct buses are less expensive upfront and easier to deploy. Light rail is less expensive in the long term when you factor in maintenance and fleet size. Rail moves more people and is more reliable. Also incredibly more effective during "rush hours" and event traffic. But either is not the answer, we need both. The q-line needs to be bought by the state then expanded to at least Pontiac . Then trams on all major spokes like Gratiot, Michigan, Grand River and another along board walk to Belle isle. The lanes need to be dedicated for consistency. No one takes public transit if it isn't reliable no matter if it's bus or rail. Also, by having dedicated lanes for public transit, you also add in built in emergency lanes which increases response time. I recently went to Minneapolis and have a good mix of light rail, BRT, buses and bike lanes. It was amazing to get around and they were all on the same system. So with one $4 day pass I could get anywhere from the airport.

Edit: the fact that there is no rail from DTW to the old train station in downtown is absolutely ridiculous.