When mobile sales are booming, smartphone thefts are almost certain to rise. That's something San Francisco and New York prosecutors George Gascón and Eric Schneiderman have been telling smartphone makers for over a year, but now they're finally making some headway. After pressuring Apple to implement a "kill switch" inside its devices, the New York Times reports that police officers in London and San Francisco saw iPhone robberies in the cities fall by 24 percent and 38 percent respectively in the six months before and after the company implemented its Activation Lock feature inside iOS 7. Over in New York, robberies were down by 19 percent and those involving grand larcenies dropped 29 percent when the police compared data in the first five months of 2014 with the same period from 2013.It's clear to see those small changes are making a difference, and lawmakers have rightly commended smartphone makers for implementing tougher security measures. However, things will move forward significantly from July 2015, when all smartphones sold in the United States will come with an anti-theft tool set as standard. Apple and Samsung are on board, as are Google, HTC, Huawei, Microsoft (and Nokia), Motorola and the country's biggest wireless carriers. It could save collective total of $2.5 billion a year in replacement costs and insurance fees, and some major headaches too.