IRS Could Search Warrantless Location Database over 10k Times
vice.com
vice.com
Any app with a facebook login button, for example, is transmitting some of your activity data (with coarse geolocation from your IP) to facebook, even if you don't use the facebook login button.
Google and Apple could ban this sort of stealth location tracking (via the widespread practice of ad company SDK embedding) in the mobile app stores, but they don't.