Costs of digging up the road to individual premises are fine, when you're not doing a whole street at once.
Actually, the way to do it is dig up a whole street at once and combine it with whatever other utility work is required. Individual access invariably means expensive resurfacing down the line. While you can't expect private companies to pay for this*, the state can quite easily and it's better use of capital than giving it to the banks. It can also afford to calculate an ROI over a longer term which means lower rentals. Higher take-up could conceivably lead to higher productivity, or at least higher market activity.
* Well that was until the central banks started to hold interests rates down artificially. Correctly pitched (reasonable annual return, say 5%) and this could be attractive to pension funds who are starting to get worried about cashflow. "Correctly pitched" means: not as fecking stupid as the promised returns on the proposed new nuclear power station. The state would also have to sweeten the deal for more remote areas where the sums otherwise won't add up.