Earlier quoted context omitted.
The advantages to streetcars aren't limited to what I suggest. They also include noise and air quality advantages (hooking up to municipal power sources instead of carrying their own engines), human advantages (they tend to be more comfortable than buses, both because of road quality and size), capacity, and so forth. There are many, many situations where buses (ideally, electrified ones) are the right choice. But th…
>hooking up to municipal power sources instead of carrying their own engines You can do that with a bus >they tend to be more comfortable than buses, both because of road quality and size (1) You can make bigger buses if you want (2) There's little difference in a streetcar on a track and a bus on a flat road. And it's a lot cheaper to get flat roads than to lay track
Nontrivial after adding the second deck (common in UK & Hong Kong), or an articulation (common in EU and mainland China) However for tram, the upper limit is your platform length. It's also common to run single trains off-peak, couple two together during busy hours to double the capacity.