I know my area very well, and can still be significantly off when picking the right route due to unpredictable traffic patterns. Google maps can't even tell me

I know my area very well, and can still be significantly off when picking the right route due to unpredictable traffic patterns. Google maps can't even tell me the best route off-peak. It's fine for travelling abroad when all you want is a route that gets you to where you want to go in reasonable time, but I would never expect Google's directions to be optimal (at least in an urban setting, where taxis are used most). As someone else has commented, this is definitely a drive to centralise reliance on Google Maps by making it the de facto standard for defining the best route (you can't go back in time to try a different route, so it won't be viable to argue that Google didn't provide the optimum route).