Quick google brought me to this
https://nbnmyths.wordpress.com/how-a...paying-for-it/
"The $27.5bn Government component of the NBN is funded by debt, through the issuing of Australian Government Bonds. That is, the Federal Government offers our AAA-rated bonds to investors, at an interest rate of about 4% (depending on the term).
The NBN however, will provide a return of about 7%. This means that (once the network is operational), the NBN will begin repaying those bonds at a higher rate than what Government is paying on the debt. By 2034, the entire Government investment (including the interest) will have been repaid by the users of the network, leaving the Government owning a valuable asset (the NBN network) and no associated debt."
Is this basically what you're saying with government spending and tax? If so, where does the tax money go to, and a possibly related question; how is the spending that doesn't create revenue generating assets funded? Or is the point that if you use a big enough frame of reference that all of their spending will create revenue some way or another