AK-47 is not one weapon. There are many different types of construction and even more derivatives. Stamped (cheap) or milled (expensive, more accurate, does withstand abuse like sitting on the gun) parts, it does make a difference. Open sights and wood stock also indicate cheap construction. Quality of ammunition also plays a big part in accuracy, but I'm not going there.

Even the AK-47 derivatives have several generations. For example Finnish Rk 62 (current Finnish standard issue service rifle) was licensed to form a baseline for what was to become IMI Galil. http://www.dnmsport.com/GALIL/historygalil.htm

(Disassembly + assembly of Rk 62 takes about 40 seconds, it has five parts)

No modern army uses AK-47. So it shouldn't be compared to SA80.

The bottom line: AK-47 is simple and good enough to be effectively used by even the most inexperienced soldiers. It also requires the least amount of maintenance. Precision tools require more experience and always have drawbacks (like gain accuracy - lose the ability to shoot effectively through walls). Multi-purpose tools are compromises, of which AK-47 is the most battle proven.

It has better accuracy than M14, AK's contemporary foe. AK's reduced caliber revision, AK-74, has it on par with (similarly reduced caliber) M16.

"It has zero accuracy..."

Not so. Watch what happens at 1:09 of this video of the 2005 Tyler, Texas courthouse shootout. David Arroyo (the guy with the AK-47) cuts down running civilians, cops - in short, everyone he sees. He's using his AK-47 in semi-auto mode (one trigger pull = one shot) very effectively against moving human targets:

http://www.youtube.com/watch?v=pVGmSzV00-Y

One lesson from the video: stay behind cover while looking for a shooter.

I was with you until the last line... seriously?