Well, here it is:
I'm a little bemused by this
Aluminium wire is crap, everyone knows that - and what's with the 'oxygen free' rubbish, that's just a marketing term used by HiFi advertisers to con the gullible.
That length of wire of that cross section should be <5 mΩ in aluminium, and <3 mΩ in copper. At 6 A the heat dissipated should be <0.2 W with aluminium and < 0.1 W with copper.
Anyone who is trying to save fractions of a penny on 5 cm of wire by using CCA instead of copper, or who is trying to hide that the wire is cheap by using CCA which is fatter for the same resistance, isn't going to be making the connections properly. It could also be that the wire had been bent too much on installation, and aluminium would crack strands more easily than copper.
If everyone knew that then there wouldn't be such a large market for it, would there?
Lots of producers/suppliers = demand:
The U.K. doesn't represent a sampling of the World markets.