alt Hacker NewsI was thinking this too - my guess is the cars simply wouldn't offer rides on days with really poor conditions.
Toronto's winter driving is normally very reasonable compared to Montreal. My guess is the Waymos operate some ~355 days a year, taking days off after big storms.
This could still be a problem. Human drivers are still available on these days today, and if services like Waymo take over and theres less Uber (et al) drivers, then we'll have no support on the worst days.