Just remember NBN get a $24-38 cut for the AVC charge, then another $15.75 per 1 Mbs of CVC capacity.
So do the math on a cut price $65 plan, needing to also pay for backhaul from the NBN POI, then some internet transit, staff wages, rent, equipment costs.... There's also the rackspace rental at the NBN POI. ADSL was cheap because a lot of the infrastructure has already been depreciated.
CVC is not scarce. NBN have tens of millions of dollars in equipment being underutilised. Increasing utilisation would barely increase NBNs cost structure. Cutting the price of CVC much more rapidly would just delay the revenue, no eliminate it, as competition would force RSPs to buy more CVC, which means people use more and you get a faster version of utilisation growth than we already have.
Definitely RSPs need to stop highlighting the up to speed. Possibly the ACCC could force RSPs to provide average peak time speeds for each POI so consumers can shop based on price and performance much easier than they currently do.