Why is Flock bad, but Stringray or PRISM good?

The federal government, for decades now, has had full access to every phone call, text message, and email that every single American makes and sends. And, collectively, we've been perfectly ok with it. The Feds and local authorities have been able to track our movements via the Stingray cellphone tracking device for decades, and, we've allowed it.

What makes Flock different? Why is it a bridge too far? The movement against Flock has been a growing, and most surprisingly, bipartisan one. Do most folks feel that Federal goverment employees can be trusted more than local cops? Is tracking faces and license plates somehow a greater privacy breach than the ability to listen to your phone calls?

I don't like flock. I don't like stingray, I don't like the NSA's personal little citizen search engine. Yet, so far, only Flock has garnered enough ire to actually cause politicians to fear their re-election chances. Why do you guys think that is?