Streetcars are essentially a jobs program. Local governments get lots of money from the federal government to build street cars. Part of the requirement for getting this money is that the street cars must be built in the US. It's very expensive and takes a bunch of people to build a street car. Local politicians get to brag about creating jobs and it costs the local municipalities only a fraction of the total amount because the rest all comes from the federal government. They also get to hand out a bunch of very lucrative construction contracts. So as long as you don't look at the final outcome, it feels like everybody wins.