While I agree to some extent that some surveillance may have some collective benefits in very specific and legitimate cases, one has to stress that it all depends on who is in charge of the surveillance, what the data is collected for, and when the data is analyzed. If a multinational private company pulls the strings, or when the data is collected to increase their revenue, or even when the data is analyzed a priori regardless of any criminal issue to investigate (which would not solve this one crime, but greatly discourage others crimes), that surely leaves some concern.

Also, where to draw the line between privacy and public safety will of course vary a lot among people, but a "certain use of location servers to know where users are" is in my opinion already way beyond the line. Especially when location history also gives knowledge of where they were before, what are their habits, and when did they change them. People whose location might be of interest to the authorities* should be tracked by other (targeted) means instead of thanks to massive surveillance. Rough location thanks to GSM antennas is one thing, so far not really analyzed for no reason in my country, but GPS tracking with Google Services is a plague.

* I am not talking about marketing reasons for knowing people's location because I do not think they should be deemed acceptable.