As a counterpoint, Prague is building new trolleybus lines at a somewhat regular pace after having abandoned them in the 70s.

Granted, these trolleybuses also have batteries and only spend about 1/2 of their journey under wires.

Yep, hybrid trolleys / battery trolleys are really cool, as they provide the flexibility of batteries to e.g. work around roadworks and blockage, but allow for a more distributed electricity consumption thanks to partially fixed routes / overhead lines.

The poles also make for convenient overhead charging docks, which you can add on a somewhat piecemeal manner. With some automated guidance, that means you can charge the buses at long-wait stops or when they wait to run the route back even though they're not a a depot, without the need for an "accessible" charging infrastructure (or the driver needing to move out, go open an electric cabinet, plug in a charge cable, then remember to unplug before going back out).