Difficult to compare BT and VM
VM's network is ONLY used by VM.
BT's network (from the exchange to the punter) is by law open to being used by all sorts of other carrier. eg Sky, TT etc etc.
So a bit of BT fibre may well be used by half a dozen different other ISP's. Then you have all the people moving from one to another one. For a level playing field when it come to us punters you can't load it all onto BT. Very difficult to apportion what how much should be off loaded to other ISP's.
The same goes for those with kit in a BT Exchange and those without.
IMHO, it is rather difficult to use the same valuation model on BT's cables than on VM's.
The crappy VM network up my street has not been upgraded since NTL put it into the ground god knows how many years ago whereas the BT network is a lot newer.
Yes I have an axe to grind against VM. My house did not exist when NTL laid the cable so they (VM) won't connect me to it despite it running less than 10ft from my property. I'll even dig the trench for them but nope. BT OTOH, did connect it up.