"why private companies do not make such fiber networks?" It's a bad investment. There is a large front loaded capital cost and a long, slow payback over decad

"why private companies do not make such fiber networks?" It's a bad investment. There is a large front loaded capital cost and a long, slow payback over decades. Build-outs are plagued by difficult problems involving multiple levels of government and incumbent roadblocks. Private investors simply can't entertain things with such long time horizons, particularly if it involves legal and political entanglements, unless the eventual payoff is enormous. There are better, faster opportunities. In the early days of electric and telephone service in the US we had a different model. The goal was universal service and it was supported by subsidies, special status for incumbents and legal force that precluded most of the roadblocks. Had this not been the case both telephone and electric service would be what broadband is today; a spotty hodgepodge of cherry picked areas servicing mostly well-to-do urbanites.