Because it’s one step closer to Orson wells 1984. When the pandemic hit my phone had an app downloaded to it. It was to track just this. It was turned off but hard to find unless you knew where to look. Many people I told about it checked their phones with the same results. Granted it was off, but how hard would it be to turn it on at will without the owner knowing. The govt isnt know for handling personal data properly. I could see a DA asking for the data to prove someone was at a specific spot. Yes they can do this now but there are steps to it.
On top of it these phones are not govt property I have to pay taxes for the honor of owning one. Until the govt pays my phone bill they can’t have my data. I try to restrict private companies ability to do the same thing.