They would also need to provide infrastructure for charging the fleet, possibly multiple times a day depending on what the routes look like, which is a signific

They would also need to provide infrastructure for charging the fleet, possibly multiple times a day depending on what the routes look like, which is a significant cost if they want to do more than one battery worth of a route in a day, even if they did have short enough routes that they could do overnight charging for everything that's still a lot of power draw and would need expensive electrical upgrades. Sticking with gas there's no further infrastructure investment required.