Battery use on Android 8.0.0
That explains a lot!
My use case, and I suspect most users', isn't so much for tracking vehicles as people; My family uses it as a way more private replacement for Google Latitude. So most users are indoors most of the time, but when they are driving, GPS will be available. Therefore high accuracy would be disastrous for battery life since as you said, GPS will always be trying like mad to get a fix. But medium accuracy is awful once they're outside.
I'm not sure what a good solution would be then. GPS fix should probably never take more than 2 minutes. Way less for AGPS. Try for a GPS fix for 2 minutes. If it doesn't work, stop trying, fall back to medium accuracy for 5 polls, or if movement of more than 100 meters occurs, whichever comes first?
I see on Lost that the project is somewhat stalled... Shame.
If you are indoors, GPS will always be ON because it can't get a fix. Doesn't matter what frequency you select.
Medium accuracy doesn't fall back to GPS. Logic is defined in Lost library that we use:
https://github.com/lostzen/lost