[Irian]

That would be very distinctive. With all the cyber/bio out there, I doubt there are many people that wouldn't have it replaced.

With so many people poor and SINless, I think there are enough :-)

[Dead Monky]

Yeah, but how often does an arm actually get torn off?  (Or otherwise removed.)  The odds of it happening for the average person are pretty low.

[Kontact]

It's easier than you think to lose an arm with no medical support.  Amputation has long been the solution to gangrene from a bullet wound. 
There are parts of the barrens where the fires never go out and poison gas is so thick that you can't see your friends dying next to you.

You might be thinking of the wrong average person.

[FastJack]

I'll give you that it may occur with an average person in 2072, but we are talking about Shadowrunners here. If they were missing an arm when they started, then they would either work hard to get it replaced later on.

[Dead Monky]

I was talking about the average sprawl resident, not Runners.  Obviously, Runners are going to have a much higher risk for limb loss, face shootings, and testicle stabbings than your average wage slave, or even sprawl squatter.  And I'm sure how high of a chance those in the Barrens would have.  Most people aim for center of mass, the torso, not limbs, and most bullet wounds are in the torso.  But there are other ways to lose a limb than bullet wounds.  Ghouls, collapsing structures, passing trains, etc.  So I get your point.

[Inverse]

It easy to lose limbs when you're running with a sammie who critically glitches on every attack roll with a damn vibroblade sucks at life.