How can Google do this? By anonymously gathering data from people like you and I, travelling using the software and thereby passing information back to the mothership on speeds on every road and at every junction. Which needs a consent form, apparently being shown in some regions now, according to 9to5Google:
Google Maps users on Android and iOS today are seeing a new prompt that (above) explicitly permits the app to crowdsource their “navigation data.” Notably, live turn-by-turn navigation will not work unless you agree.
Maps has always used this location data — along with transportation mode and sensor, like barometer, data from your device — to offer real-time information, with Google last September saying that over 1 billion kilometers are “driven with” the app every day around the world. That corpus of “navigation data” makes possible alternate route options, traffic status, and ETAs, as well as turn-by-turn navigation.
The company is now explicitly laying out what powers that last capability to end users and requiring them to agree to crowdsourcing to use it. This is presumably related to the “we protect your privacy” messaging that started at I/O 2021. Since May, Gmail, Photos, and Drive have all displayed in-app banners emphasizing privacy.
If you don’t agree — i.e., selecting “Cancel” — to contribute your data, you won’t get live turn-by-turn navigation with voice feedback, e.g. turn left on [X] Street. Users will instead just be offered step-by-step directions as a static list. “Learn more” links to a support document.
Which is all absolutely fine, of course. Clever of Google to word things so that the dialog says 'Start' and not 'OK' or 'Accept'. I mean, everyone wants to 'Start' when travelling, don't they? And there really is no suspicious tracking going on here, Google just needs data points in real time on how fast traffic is going on every road so that routine for others - or perhaps for you - can be calculated and adjusted as needed.
Amazing software. I run it on iOS and Android - and even Windows phones before that, via third party clients, which still had access to all the traffic and navigation data.