To be fair, Arborwayfan, when I took Driver's Education through my high school, that nugget of knowledge was certainly not on the curriculum, since I was a resident of Ellsworth Maine at the time. And when I moved to Massachusetts to attend Northeastern University and traded that license in for a Massachusetts one, I don't recall any further testing required. Nonetheless I paid attention to the numerous signs along Huntington Avenue and used a bit of common sense to deduce you're not supposed to blow past a streetcar stopped with its doors open. I've been on both ends of the "argument", as a rider of the E line making that tentative step down and fearfully looking to the right around the edge of the door, and as a motorist on Huntington and South Huntington Avenues doing what I was supposed to do (and often getting angry honks and middle fingers from fellow motorists for my troubles). In Toronto, you're supposed to stop your vehicle at the rear quarter of the streetcar, and people do it, and it works well. Here, the law reads different, but the concept is very simple - use caution when driving alongside a streetcar, be mindful that when it stops the doors might open, and be prepared to stop short of any open door anywhere along the length of the train. That might be inconvenient to those who like to zoom up and down Huntington Avenue as if it's Route 9 somewhere out in western Massachusetts and and not Route 9 along a city street in Boston, but to me getting stuck driving alongside or behind a streetcar is about as too bad so sad as getting stuck behind a truck on a hill out there on 9 in the Berks. It's not ideal, but if you can't get yourself out from behind the situation without being dangerous, then too bad, just ride it out.
Anyway, back to the Type 9s, if the T doesn't want to run Type 9s on the E, IMO garbage reason or not, I suppose that's up to them. I guess on the plus side there's less chance for one to get damaged in an accident.