There are a number of contributing factors:

• We have a shortage of around 2800 truck drivers in NZ, so there's a lot of pressure on the existing drivers to work long hours to meet demand. Unfortunately, high demand and scarcity of labour is not translating to higher wages.
• Truck driving doesn't actually pay that well. A class 2 driver (small truck) might make $22/hr, while a tanker driver pulling explosive liquids might top out at $45/hr. Couple this with the legislated maximum 13 hours per day of work time and up to 70 hours before a mandatory 24-hour break and you've got a recipe for overwork.
• Large transport companies work on thin margins and don't necessarily pay promptly
• Owner drivers have a huge investment in the truck itself (a new B-train and tractor unit can top $600,000, or be $6000-7000/month for 5 years on lease) - lots of financial pressure, pressure to cut corners, not do pre-start checks (you can get 5 minutes' further up the road if you don't check your truck)

There is also a worrying media narrative that influences our thinking about truck crashes: media frequently couches a crash as a truck hitting a car and not the other way around, even if it was the car at fault. Truck drivers are professional drivers and receive much more training than car drivers. They tend to be more aware of their surroundings and the fact the vehicle could weigh up to 60 tonnes. They are at fault in around a third of fatalities that involved a truck. There are lots of stats here: https://www.transport.govt.nz/assets/Uploads/Research/Documents/8764070595/Trucks-2017.pdf (delve into it as it's multi-faceted and too detailed to explain here)

So, the obvious way to reduce fatalities from truck crashes by 2/3 would be to stop other vehicles crossing the centre line into their path, performing dangerous overtaking manoeuvres, etc. But that would require driver training, which is a discussion we're having in a different thread.

The other third almost certainly will be helped by better enforcement of work-time rules so that drivers aren't driving fatigued, new truck technology (e.g. ABS isn't anywhere near universal, let alone the kinds of tech we see on cars), trailer rollover and stability training using something like this tanker https://www.masterdrive.co.nz/courses/heavy-vehicle-stability-control-driver-training-programme/ so that drivers can experience what it's like to be in a truck as it starts to roll, etc, etc.

Peter Gallagher is demonising roads, which is wrong and is not productive. When we accept the 'roads are dangerous' angle, we give ourselves permission to lessen our responsibility for the carnage that we create on them. Roads themselves are rarely dangerous, it's drivers not driving to the conditions that is the problem. If you want to stop crashes, improve the standard of driving.