All the trolley bus routes were originally streetcar routes built out a century ago. Tbh I'm not aware of them ever installing new trolley bus routes.
Trolley lines are going to be expensive to install and maintain. Even without fast chargers they still need similar equipment to convert to DC for the trolley wires.
A quick search gave me a TransLink report which probably has some good details: https://www.translink.ca/-/media/translink/documents/about-translink/policies/translink_low_carbon_fleet_transition_plan_2020_02_24.pdf