Before launching in any city, you have to validate that you can handle the idiosyncrasies of its driving environment. Perhaps the business side decides that Detroit isn't worth launching in, but <other snowy city> is drivable 200 days/yr and that's enough to warrant launching an intermittently-available service.

My ultimate point is that AVs can cover a lot of ground from a business perspective without getting to full universal-availability. This is helped along by a combination of validating each city independently[1], limiting operating conditions, and safe-fallback teleoperation for occasional use.

Validating a 2021 AV in a snowy environment isn't an inherently harder problem than validating a 2016 AV in a normal environment (with a safety driver), and a similar approach will be applicable.

[1] Presumably less and less narrowly each time

If not, the robotaxi could drive itself to Florida and leave any customers who relied on it up north in a lurch, and also mess up the traffic and transportation economy of Florida in the winter. Screwing two economies with one car = bonus.