We're in Argentina, Not the US -- AK47s aren't exactly available at the rates seen in that country. You've been living in the US for too long -- take a little trip to Canada and try to understand that in the large majority of non-warfaring countries, carrying a weapon is not considered normal.
As Grazie said these crimes do occur in the rest of the world, and with more frequency than here. Also, La Nacion and TN report on these every time -- to me the fact that they hit the news every time means that people are still shocked and they don't just see it as a day-to-day occurence.
I think we should remember that unlike in the States where everyone and their dog pulls out their gun at the drop of a hat, a lot of the robbers here don't even possess guns, and most robberies see the end result that the owner just gives them their money and they leave without harming anyone, or the robbers get freaked out about something and flee.
The guards at countries are paid well -- if you want your country to be secure of course you pay your "front line" a good salary. If you've got a good guard, they do their job -- one guy even took a bullet in the stomach and his hand while trying to stop some men coming in. Realising that they may have actually killed a guy (suddenly stepping up from armed robbery to murder) the guys that were trying to get in fled the scene, never even entered the Country. The guard is in hospital and should recover.
The robberies are not exactly organised either - it's usually a few guys coming in over a wall -- take a look at this pic from Good Airs and you'll see that you don't exactly need to be an expert planner to figure out how to get in:
http://www.goodairs.com/2007/04/bubble-generation.html
Also, if we were to apply lessons from the excerpt below, it would seem that the robbers are getting their guns from the people that they are robbing:
El Olivos Golf Club (foto), de la localidad bonaerense de Pablo Nogués, partido de Malvinas Argentinas, fue asaltado el viernes último por tercera vez en dos meses y por segunda en una semana. Allí, por lo menos dos hombres entraron en la casa del empresario Víctor Andrés D Atri, cuando éste se encontraba trabajando en la Capital, y se llevaron 9000 dólares, un reloj marca Rolex, dos pistolas 9 milímetros, una Beretta y una Walther.
A este hecho se sumó ayer a la madrugada el robo en una casa del country Los Pilares, de Pilar, donde dos delincuentes sólo alcanzaron a sustraer la cartera de la dueña de casa, que dormía, al igual que a su marido, sus dos hijos, de 5 y 12 años, y una empleada doméstica. Al ser descubiertos, huyeron.
By the way, moral of the story above: don't buy in this country - 3 times in 2 months? Something fishy going on there.
Also if we're going to tell the full story, apartments in the city are being broken into as well. In Caballito, Villa Urquiza, and Barrio Norte. In Barrio Norte on the weekend 3 robbers forced the encargado of a building to take them to different apartments:
El episodio ocurrió el viernes pasado cerca de la 22 cuando los delincuentes ingresaron al edificio ubicado en Azcuénga y Paraguay, y sorprendieron al portero en su departamento del décimo piso.
http://www.lanacion.com.ar/904782
It really bothers me when people that aren't living in BA write about BA, Sao Paolo and Karachi in the same breath. It is evidence that this writer has spent very little time in BA. I will grant you the fact that of course there are poor neighbourhoods where I would be crazy to walk through, but hell, I wouldn't walk through most of Detroit, step foot in some areas of Chicago, or be caught in areas of DC after about 2pm.
BBW I think you've been traumatised by your time in Karachi and the US -- maybe it's time to take a little breather -- head to Canada or to Patagonia, chill out for a few months, turn off the FoxNews and start watching the CBC to get some perspective (you're in Michigan I believe, you may be able to get the signal).
But please don't try to raise the paranoia levels on the forum, people who are thinking to move here should understand that like any major city you do have to be vigilant, but they shouldn't be scared every time they leave their house.