The 30 billion to Telstra was the liberals to buy the copper network, not part of the Labor plan. 30 billion for a network the CEO of the owning company said was minutes to midnight a decade earlier.
What do you think is more efficient, digging up the footpath once and giving everyone a fiber connection, or doing it 50+ times? Because if everyone completes the line to their house, that's what will happen.
More importantly, if you're trying to start a business or provide a government service, you can't rely on everyone having a 100Mb connection, you have to plan for the lowest common denominator.