Permanent, in wall, cabling is solid core. Cheaper to make but won’t cope with being repeatedly bent without weakening.
Trailing/accessible cables are made of stranded cable.
So unless the quality/purity of copper is in question, would it be safe to assume that a sloid copper cable is more fragile, or does a twisted strand cable, presumably more versatile, possibly more expensive due to being over engineered, but provides a more consistent signal?
Again, im not taking the mick I just don’t understand the apparent disparity