Even if the Kardashians didn't use Snapchat to basically liveblog their whereabouts, this was an inside job. Her employees would know where she was anyway.
Paparazzi would have pictures of her too, and you would likely be able to narrow down her location with a knowledge of Paris and enough dedication to rob her at gunpoint.
Fans on Twitter act as a live, crowdsourced paparazzi, posting candid shots of The Kardashians in real time as they go from place to place.
A tweet of a pic with Shia Lebouf in a Tennessee diner was how those guys on 4chan narrowed down his location in order to take down his flag on Livestream.
This cannot be avoided. Monitor Kim's Twitter mentions and I bet you could find out where she was an hour ago today, with little effort.
Also, this was a plot point on the show earlier. Kylie was being stalked in real life, the perpetrator using Snapchat, Instagram, and Twitter spottings by fans to target her. As it was revealed on that episode, Kim, Kendall, and other members of the family often cloak where they really are by posting to Snapchat while in airplane mode, and then disabling airplane mode after they've left the area they posted in. The Snapchat goes up, but it isn't really live anymore, they're already gone but they've generated content for their fans to interact with.
They're not dumb.