Re: £5Bn from Government
It’s mostly down to the law. If Openreach install rural fibre and charge you less than it cost them the other network operators would take them to court for predatory behaviour and breaching the Competition Act. Openreach would lose that court case.
Nothing would kill the businesses of the alt-nets faster than Openreach rocking up somewhere they were rolling out and then using their deep pockets to sell below cost until the alt-net has gone bust.
That’s why these rural rollouts all use government funding to cover the gap between the actual cost and a cost that would be considered economically viable. Bidding for, and winning, a government funded rollout for an area is the only way around that legal problem.