Jaw vs. Virgin Media

All of the above provide an analogue line- from BT Openreach.

The companies above simply bill you for it.

The only lines truly provided by third partes (NTL/C&W/Verizon/Colt/etc) are full dress ISDN30, and the majority of the time they end up using BT tail circuits.

Oh come now, you're being unfair here. Almost every voice provider in the UK makes use of Openreach infrastructure to one extent or another, but that doesn't mean they're all just re-selling BT lines. LLU DSLAMs require significant investment and maintenance.