>>2057839This type of car is called a Peter Witt car. It was conceived to have front entry and the conductor next to the middle door. That way people could get on right away but they'd have to pass the conductor eventually and pay the fare. This reduced dwelling times compared to the usual system of having people pay right when getting on.
Though not exclusive nor unprecedented features, the triple front window and low floor at the center door are typical features of the Peter Witt car. This type of cars was common all over north America, and variants were also built in Europe, most famously in Milan, Italy where many of those trams from the late 20s are still in daily regular service.
Pic related is a Peter Witt preserved in Toronto.