As a frequent business traveler, I often make trips to our airport, DTW. Sometimes, I drive. Sometimes, I take a cab. Sometimes, I am dropped off. The miles add up. If there was a shuttle or bus or train I could take instead, I probably would. Many Detroiters might say the same, and many are studying possible solutions (currently, Metro Cab's contractual monopoly does pose some challenges to transportation solutions, but not insurmountable ones).
Each year, DTW handles > 30 million passengers. Thereof, the airport originates ~17 million passengers. If an average travel party size is two people, that means each year, Michigan travelers are making ~8.5 million round trips to DTW.
If the average round trip is 50 miles, and the cost per mile is 55 cents (that is the rate I am reimbursed at, factoring in fuel, depreciation, insurance, etc.), then driving to and from the airport is costing Michiganians about $234 million per year, or $2.3 billion over a decade. The fuel alone (at 25 miles per gallon, and $4/gallon) results in $68 million in gas being burned by our citizens each year, or $680 million over a decade sent to Texas, Alberta, or Venezuela.
I'm not sure what an optimal network to connect Michiganians to the airport would look like, but in a 2006 study, SEMCOG estimated that transit from Ann Arbor to Detroit (passing through DTW) would cost $0.6-3.0 billion to setup and $25-110 million to operate annually (on the higher end for light rail, on the lower end for buses). If the new Regional Transit Authority can put together a network that serves even half of the local airport traffic (~4.2 million round trips), saving Michiganians collectively $1.15 billion over a decade, I'm pretty sure it would more than pay for itself over time (not even including reduced traffic, pollution, wasted time driving, ridership fees, etc.).
Anyone should be able to land in Detroit and just hop on a shuttle or
bus or train to downtown Detroit, Ann Arbor, or other places without a
hassle or expensive taxi or rental car, like they can just about any
other major city in the world. Jobs, economic development, efficiencies, connectivity...connecting Metro Detroit to the airport with reliable public transportation is a no-brainer.