The government tracking everyone's location all the time would be/is a gross infringement on privacy. The government tracking everyone's location for a limited time period in order to curb a deadly epidemic seems much more reasonable. The difficulty is trusting them to give back that power when the crisis is over. If not for the experience of the Patriot Act, I'd be more inclined to give the benefit of the doubt ther…
General levels of social distancing can be gleaned without phone location info. All you need to do is have police drive around and look.
The problem with requests like this, for detailed phone data, is that everyone can imagine vague benefits in the abstract, and wants to be helpful, so you're more willing to cede protections of privacy (which are ultimately protections of liberty). But those vague abstract benefits don't necessarily translate into actual benefits if you think it through.
I don't see anything necessary about phone surveillance at this time whatsoever. What is necessary is mass testing.