#24 and #55 were wired several decades ago. Once Muni moved to more "normal" diesel buses (after the GM fishbowls) they were iffy for the route. Rather than break up the fleet into "hill" buses and "freeway" buses and "normal" buses like with the Macks, they wired the steep lines.

The main issue with battery-electric buses and hills is that, unlike trolley buses, they have limited power supply. It's only what's in the battery. So there's a tradeoff - cost of installing and maintaining the wires vs limited battery power (or perhaps needing those diesel hybrids).