Those business's that are paying big dollars for 10/10, 20/20 or even 2/2 up/down are paying for a fibre fed managed service with Service Level Agreements most being service restored same day or possibly even hours and if its not restored within their contract SLA then they get compensated.
Yes there are people/business out there that have bonded SHDSL services in areas that have fibre but choose not to pay for the reliable service, but when there is a noise problem on the copper in the street that takes 5 days to fix, then they wish they had fibre or a fully managed service.
Dont get the wrong idea I agree with the NBN in principle, but its never going to work until they force people onto the NBN fibre by removing the copper in the street which isnt going to happen and the current take up rate is only 10%, I believe alot lower than forecasted. Telco's are still installing DSLAMS and will continue to do so until the copper is pulled, the Greenfield Estates where the NBN is going in I believe there is no copper so there is no choice I may be wrong, just as there should be no choice after the NBN rolls thru a existing suburb.
Either way I will be paying thru higher taxes to cover the cost of the low take up or pull the copper out and give me NBN at a reasonable price.