While I agree that for most route in SF where wires are being considered, they're a viable alternative compared to battery or fuel cell (H2), I'm not so sure that batteries are uncompetitive. All costs considered, battery isn't bad (pretty good, even) where distances and operating conditions are suitable. Batteries are also, of course, used in trolley buses to allow short off-wire jaunts - at what battery size does the bus get logged as battery with on-route recharging, vs trolley with backup battery?.

H2 with fuel cells makes sense where distances and operating conditions require a long operating range with reasonable refueling time.

Once upon a time, even LA had trolley buses. They died at the same time (early 1960s) as the streetcars.

And SF does have some unique aspects for transit, including its compact nature and tradition of using public transit. Plus, electric power for City use is nearly free, being generated by the aqueduct bringing water from the Sierra. The City can't actually sell its power to PG&E ("wheeling" notwithstanding); it has to use it by itself or sell it to other municipal/public operations (like some irrigation districts). Most places don't have that kind of deal.