The power lines that trolleybuses use don’t cover an entire city. They’re only installed on the routes the buses are scheduled to run on, and only for the parts of the streets buses will use. They’re like train tracks in that way, but hanging in the air instead of embedded in the ground.

Garbage truck fleets are expected to cover every street and every block in their service area which adds up to more of a city than bus services cover since they don’t stop on every block at every house and building. The lines also require maintenance and you also need to train operators to re-establish the connections not if they drop but when they drop. Doesn’t seem worth it to me, at least not for New York.