Philly intentionally neglected their streetcar system. SEPTA is a mess for a whole host of reasons, but the main one is that all the counties involved in it have to all agree on projects. Suburbanites don't want to fund urban transit. That's oversimplifying it, but it's a major impediment to improving transit in Philly proper. Here's a good recent video about the streetcars there (https://www.youtube.com/watch?v=DYXx3CgwmHY)

And people will use transit if it's reliable and frequent. And yes, infrastructure isn't cheap but how much money have we dumped into the 6/10 rebuild and the downtown viaduct on 95? Putting tracks in a street and running wires overhead really isn't very expensive, and the savings in maintenance on vehicles that have no combustion engines, and aren't subject to potholes more than makes up for it. Trams are ubiquitous in most of the developed world, except here. Take a look at the transit networks in places like Bilbao, Bordeaux, or Utrecht. They are all similarly sized metro areas to Providence and it really emphasizes what a joke transit is over here.