Yes BT will be investing alot but there is a reason for the investment and BT will make "alot" of money from a pot investment which is not 100% BT's.
I do find the reporting of % complete highly misleading and imho a deliberate smoke and mirrors approach. I have asked BT Outreach to provide me with the % enabled purely on my exchange. I doubt they will give me a clear and honest answer but I will come back with their resonse .... assuming I get one.
Please advise how you determined the 80-90% figure. Certainly from my experience there isnt a single person I know in the area that can get FTTS. Of course I dont know "everyone" but I am reasonably well networked in the community and have also tried various postcodes and addresses through infinity line checker etc
Ultimately, BT Group are a business who are entitled to make commercial investments. Without the money invested in the commercial roll-out by BT Group and their City investors, there would be almost no FTTx availability. We would be limited to Virgin Media's cable service for those properties passed by their network, plus the very small amount of availability from niche operators and the very limited (to date) BT roll-out involving public money (especially in Cornwall).
I doubt you'll get a response to your query about your exchange area, as such a figure is volatile and commercially sensitive. BT are not a public body who are required to respond to Freedom of Information requests, and any attempt to get this information from public sector partners using FoI legislation is likely to be rebuffed under the commercial confidentiality exemption.
It is well known that an exchange 'accepting orders' does not necessarily mean FTTx service is available. The intended end-user must be served from a PCP with a live FTTC twin, or be within the active FTTP footprint. Indeed, just because an exchange is live for an ADSL service doesn't mean that it's possible to provide that service on your line - the line may be too long or of too poor quality to work reliably.
I suggest that the average member of the public has no idea about the topology of the BT Openreach network, but will understand the idea of being connected to a particular exchange. They will understand that there's no chance of service unless their exchange is 'accepting orders', and that if they are on an 'accepting orders' exchange, their line must undergo an availability check first.
Once an exchange is 'accepting orders', the underpinnings are in place for subsequent in-fill. There are issues still to be overcome with the BT Openreach system, especially what to do with exchange only lines, and how to maximise the existing FTTC investment via the likely deployment of vectoring and profile 30a. However, there will always be lines where FTTC service cannot be provided, as the distance to the FTTC cabinet is just too long or the metallic path is of too poor quality, and where FTTP is uneconomic to provide even with public subsidy.
I can't see the government imposing a 100% universal service obligation on BT Openreach for FTTx in the foreseeable future. Such an obligation looks impossible until the time when the network is becoming fibre-only. On products where there is a universal service obligation, BT are entitled to pass on a sizeable proportion of construction costs involved.