Insurance is one reason why carriers would like to lock stolen/lost phones. It prevents customers from reporting a fake loss just to get another device.I'm not saying stop this program, but I see no need for it...even if #1 was my only point. Don't lose your phone. Buy an extended warranty coverage if you think you have a good chance of losing it.
Federal law does not require a GPS in each phone. Certainly it's not common in regular GSM devices.They already can. Federal law requires that all phones have GPS and the carriers have the means at any time to locate the phone. They are only supposed to use that means with a search warrant but they have the ability to do it at any time they wish
CDMA is a different story. Verizon has included A-GPS in almost all its phones since the turn of the century. Partly to give accurate E911 locations, and partly so that they could sell location based services like car navigation even on cheap phones.
With AT&T phones, the towers triangulate a phone when you call 911. The phone is totally unaware of this happening. As you say, it's not super accurate in many cases, often about football field distance or more, but it's fast and cheap.You don't need to buy a GPS phone for hou to be tracked. Ever heard of triangulation? That's how the 911 tracks a phone that has called in, even if it's longer and less precise than GPS. In urban environments, there's a fair chance they would never find a precise, stolen phoneusing only positioning. So, smply deactivating it makes sense.
With Verizon phones, the phone itself receives GPS signals and passes them on to the network to finish calculating the phone's E911 position, including using known local radio echoes and current GPS atmospheric conditions. Your position can be calculated quite closely. Only if the GPS signal is unavailable (like inside a basement) does the network fall back on triangulation.