Because there is a non-linear relationship between money invested and the end result, and the greatest efficiency in investment may be achieved through a heterogeneous approach.

For example, if there is existing coaxial cable infrastructure in an area, it may be far less expensive to deploy higher-speed DOCSIS than it is to roll out entirely new fibre for the same amount of bandwidth. DOCSIS is easily capable of gigabit speeds, the main issues are sharing QAMs with existing cable television and the ratio of customers per headend.

Politics got in the way.

Plus, Labor should have done a better job communicating the value of (FTTH) NBN. The average people in Australia think NBN is just to watch YouTube in HD.

Especially when the current solution offers no upside (slower speed, no cheaper, a rollout that will take just as long).

I like to play "stupid or liar" when it comes to things like this, but I can't figure out which it is when it comes to the NBN decision making.