Google isn't just trying to track you for advertising. They also put a lot of effort into creating their maps, and GPS tracks are very useful for that.
A lot of people use Fitbits for workout tracking, so they must have a lot of GPS tracks that could be useful for mapping areas that are currently not so detailed on Google Maps (eg. many hiking trails are missing on Google Maps in my area)
A lot of people use Fitbits for workout tracking, so they must have a lot of GPS tracks that could be useful for mapping areas that are currently not so detailed on Google Maps (eg. many hiking trails are missing on Google Maps in my area)