Counter point police have been able to prosecute crime without being able to defacto track every single person in the US via car and the corrosive effect of having that ability outweighs the gains. Plus on top of all of that they've proven time and time again they can't be trusted to contain themselves or their collegues from rampant abuse to stalk exes, celebrities, etc. just because they can.

But if you want to find a suspect, shouldn’t you only care about where they are NOW? Not where they were 6 hours ago? How does historical data help apprehend a suspect NOW?

This is why we need, as op is suggesting, governments to tell them something doing the lines of "too bad, that's illegal and won't be permitted as evidence".

And I personally think that in some cases that would actually be a net positive for society. Like a kid disappears or a body is found murdered or a serious crime occurs. Being able to look at who was coming and going to solve serious crimes is probably a good thing.

But for tracking petty crimes and with the abuse of the system with things like officers monitoring their exes, as one example, makes the system far too dangerous for a free society. And because of that if they are going to ever get the public on board with flock then we are going to need to establish certain rights and guarantees.

For me that would be things like warrants with the exceptions in only the most extreme cases like a kidnapping or a murder that literally just happened and immediate response was critical. Next I would want a reasonable time data was stored then deleted. That is not 2 years that is like maybe a couple weeks or perhaps a little longer. Having the history of when and where everyone goes is a huge privacy risk and should not be stored forever as it is a target. Next I would want rules that it is only used for certain investigations and crimes. Yes to violent crimes and sexual crimes and crimes against children and obvious things all of society can easily say yes those things are bad. But for most other crimes it should be constitutionally forbidden. Think of how laws and public beliefs change over time. Imagine this years back when being gay was a crime. Or tracking people who go to an abortion clinic.

I could go on for a lot longer about how this type of system is dangerous in so many ways if not governed by very well thought out rules and rights given to the public. It is sad that the operators of these systems don't want to meet in the middle to something that most of the public could get on board with but they obviously know that total surveillance is very valuable data to have on people.