New builds
Doesn't help that new housing doesn't seem to automatically get new broadband options when constructed, at least not in all cases.
I live in a new build from ~6 years ago, on a new estate that has about 85 houses. Rather than dropping a new cabinet into the estate, they ran all the copper cables down to a cabinet on the nearby main road, that was apparently undersubscribed. This was an older model cabinet, so not even FTTC, let alone a FTTP options.
My broadband dropped from around 40Mbps in the old house (which also had no FTTC or FTTP options), to ~30Mbps at the new house.
Took another 3 years before they finally updated the old cabinet to the FTTC version, so I can at least get 80Mbps now (the max available).
As far as I can see BT wholesale basically do everything reactively. They didn't automatically upgrade the local cabinet, despite all the new houses being connected to it, but instead waited for enough people connected to the old cabinet, to register their interest in FTTC, and once a threshold is met, it gets added to a list somewhere and eventually gets the upgrade.