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.
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:
There is an even more awsome version available in North AMerica/Canada. The Mine car version is built for underground mine use.
Basically the original Hilux with sealed bearing everywhere, guards over everything that can break when a rock drops on it, loads of power take-offs and an interior that you can wash down with a hose.
It even has cup holders (although not a multi-screen DVD surround sound)
It can just about fire a full mag before over heating.
To go from safe to automatic fire the safety lever makes a noise that alerts people in the next country
I'll stick with my SA80 thank you