Have you ever tried putting yourself in the shoes of people who leave their GPS on? Can you see how much better the user experience is? Can you understand why someone who never had a negative experience involving their location data might prefer to leave their GPS on?
I leave my GPS on all the time. I love going back in time and see where I was at any given time. I can download the data and correlate it with a bunch of other metrics I keep track on. If it wasn't free, I would pay for it.
I'm not floored that you turn your GPS off. I've met many people just like you. Some of them had traumatic experiences in the past, others generally don't think other people are trustworthy. I can respect that. Just don't assume it's the default sentiment, because it's not.
Here's an interesting survey about trust:
https://slatestarcodex.com/2017/10/05/ssc-survey-results-on-...