Helpfully, the report quantifies the scale of that failure for us, with a table estimate the emissions impact of each policy measure:

So, the ETS, which covers the non-agricultural half of our emissions, is expected to reduce emissions by ~9.5 million tons a year in 2030. Meanwhile, agriculture, the other half, is expected to reduce emissions by 95 kT / year - about 0.27% of their total, or about 1% as much as the rest of us. To compare it with other policies, EECA's Efficient Products Programme, which promotes LED lightbulbs and puts energy-star stickers on fridges (so, taking a small amount off the ~8% of emissions which result from electricity use) is expected to save 234 kT/yr in 2030 - or about two and a half times as much as our most polluting industry. So, farmers are expected to do less to help than you buying an LED lightbulb.
And its worse when you consider that that 50% of emissions is produced by, as National keeps saying, 23,000 farming families. Who are expected to do a hundred times less than the rest of us, while being subsidised by us forever.
As I've said before, you cannot compromise with physics. If we are to achieve meaningful emissions reductions, let alone the ones necessary for human survival, farmers must do their part. And that means not just ending dairy growth, but a massive reduction in the herd. Anything less, and we are simply not going to be able to solve this.