My accusations of low-balling were sparked by Turnbull's whiteboard explanation of the economics of rolling out fibre-to-the-node rather than fibre-to-the-premises. He didn't offer specific numbers but clearly said that the cost of rolling out fibre to every home in a FttP network is "typically three to four times" the cost of rolling out fibre to street cabinets in a FttN network.

Turnbull then drew a line of this graph to illustrate that it's not worth building a FttP network because "the marginal utility goes to zero". In other words, by opting for FttP we'd spend a lot more to offer faster download speeds which people wouldn't pay for because they don't need it. The jump from 10Mbps to 20Mbps is a lot more valuable to people than the jump from 40Mbps to 50Mbps. Eventually people reach a point where they won't pay any more for faster speeds – that's the zero marginal utility line. The expense of FttP puts it well above this line on Turnbull's graph.

Meanwhile the graph's FttN column comes in very close to the zero marginal utility line, because FttN is so much cheaper than FttP by Turnbull's calculations. While Turnbull doesn't use the phrase "multi-technology mix" in the video, the obvious take-home message is that the government's NBN plan is a better deal for Australians than Labor's FttP plan.

Turnbull refutes my low-balling accusations by pointing out that the Cost-Benefit Analysis does allow for the extra costs of the multi-technology mix plan. My criticisms weren't aimed at the Cost-Benefit Analysis, they were aimed at Turnbull's whiteboard lesson. While he makes some valid points in the video, it is misleading for Turnbull to use an FttN versus FttP comparison to justify the government's new-look NBN.

Tunrbull's graph might be valid if you were comparing a national FttN rollout against a national FttP rollout, but that's not what the multi-technology mix proposes for Australia. You can't realistically compare the cost of FttN against FttP in Australia without conceding that, under the government's plan, the cost of rolling out FttN brings with it the extra costs of repairing and maintaining the copper network as well as extending and upgrading the HFC cable network. There are also the possible costs of coming back later to extend the FttP network in places where FttN is no longer up to the job.