I respectfully disagree on Google being entirely transparent about tracking location, especially if you run Android + Google Play Services. I have a tablet (Pixel C) that runs LineageOS + Google Play Services and a Phone (Nexus 5x) that runs LineageOS vanilla (no MicroG, no UnifiedNLP, no Google Play Services). Some things I have noted:
- When you install MicroG/Google Play Services, they take over location services (i.e. they run in /system/priv-app, and if you disable their location, location on the device is disabled totally).
- Android by default has the default on option to scan wifi and Bluetooth when you turn them off to find wifi/bluetooth and coorelate it to your location.
- On my Pixel C, when if I try "high accuracy" or "battery saver" mode Location services, Google Play has tried to force me to agree to their location tracking and I have disagreed every single time. Location services does not work if I use "device only" (which is supposed to only use GPS).
- I have noted that on my phone now, if I disable location and then reenable it when I have moved more than 20-30 miles, the GPS has to reacquire the signal and can take up to 2 minutes (I also tried it when I drove several hundred miles, it took several minutes to reacquire). This is indicative of the GPS module being off totally. This was not so when it had Google Play Services on, it was able to reacquire my location extremely quickly, sometimes almost instantaneously even if I moved a long distance. I suspect that Google Play was still tracking my location even if I turned off location services (due to it totally controlling my location).
- EDIT: Another interesting note is that on my phone has had location services off and then turned just back on (i.e. no GPS lock), it appears to give the last time GPS was acquired as my current location. OSMAnd shows that location but says it doesn't know my location, but other apps do not realize that. I am suspecting that Android does not necessarily have a "stale" location, just the last reported location.
Putting my tin foil hat, I hypothesize Google anonymously tracks your location even if your location services if off (allowing them to do traffic, how busy a restaurant is, etc.).
EDIT: As correctly pointed out, networked assisted GPS is a thing, and may also play into the differences in GPS reacquiring. I believe that network assisted GPS is in AOSP. When I turn on and off GPS in Android, it appears to have the almanac for where to look for satellites based on SatStat, and how quickly my phone acquires the GPS signal is a function of where it used to be compared to where it is now. In addition, UnifiedNLP [1] scans for networks/cell towers and correlates it to location, it does not appear to implement networked assisted GPS.
[1] https://github.com/microg/android_packages_apps_UnifiedNlp