Maybe because tracking down the address for a Jesse W. in SanFrancisco isn't that hard (you just need the right website), and after that... Somebody already pointed out that a "Burglar Me Please" app would be banal to write: you just walk along SF, and the app will tell you which owner is home and which is away, and how far s/he is; correlate with Facebook (is he married? is he so young he might be sharing his flat?) and you get a list of easy targets in the area.

It's not only about where you are, it's also about where you are not at any given time.