Because of the astronomical cost involved in running fibre to some premises. And not even talking about city vs bush - two city dwellings in close proximity can have vastly different cost of installing fibre.

I would qualify my original statement with 'as part of a NBN-like project'. I didn't intend to suggest that not every home should have fibre, or in deed will have fibre at some point in the future, just not at the tax payer's expense.