You have contractors who are reaching the next stage
every week ? Do you know how lucky you are ?

Then you are not the boss, little old you, it's not you these roadlayers are answerable to but a much bigger force.
They'll be keen to get the roads done, and done properly, because they work for the developers, not you. Chances are the developers have not sold every house 'off plan', as you bought yours, but will have to sell some when these are finished. The developers want to sell these at the best; persuading buyers that the development will be perfect for them is not so easy when they have to be guided through some quagmire up unmade tracks .Most buyers lack any imagination and have to be shown
exactly what they are getting; that's why developers have show houses.
Nothing looks or seems untoward from what you say and show.
Do you have official inspections in Australia ? I'd be surprised if there's not something like in the UK: Here there are two guarantees on newbuilds. First of all most builders issue a National Housebuilders' Certificate which guarantees the work for the first ten years. Second, and in any case, no house is saleable until there is an architect's certificate that the work has been done satisfactorily according to plan and specification. It is unheard of to pay for an independent survey of a newbuild.
The real hassle with a new house is in the detail. It's the 'snagging'. It's the paint on the light switches, it's the cupboard door that doesn't quite close properly, it's the myriad of little annoyances and tiny defects which you may not notice at first but which ought not to be there. These don't fall under guarantees in the UK ( they do in France, but I doubt whether Australia is closer to French practice or law

) So before you take the keys make absolutely sure that everything is perfect first and don't take idle words about fixing this, repairing that, correcting the other;prepare a written list of defects (here it's called 'a snagging list') and make sure that it's signed by the developer or acknowledged in writing by them as correct and the defects shall be rectified by them by some date. There should be a site manager or agent of the developer who'll come round the house with you prior to you taking final possession who will do this. Reputable developers anywhere give you a period in which to find these faults and will return to see to them. (Again, in France that's the law but Australian law may not be so stringent )_
Good luck in your new home to be and welcome to Answerpool !