Having worked as a fencing contractor in rural Australia in years past (as well as on my family farm of some 1100 acres) I can say with certinty that wire of any sort (let alone barbed/ razor) is really expensive! The rope thay use is not dynamic climbing rope, but a simple el-cheapo nylon based rope. It is probably less than a tenth the cost per yard/ metre than wire. Roes really are no deterrent to human illegal ingress or egress. We all see how oft and easily they are ignored, hopped and so on. That said, wire does pose a serious hazard to land living wildlife, and can become clogged with leaves and detritus much more easliy. This can be both harmful and beneficial though. It has the effect of slowing or stabilizing erosion pathways and so on, rather like those avalanche traps in the alps you see. So it can be good for the environment, though a hazard to wildlife. Visibility is much more of an issue in deterrence values. Deer etc can easily jump these IF they can see them, which of course is almost impossible after a few months. Hence in Australia and NZ a lot of farms etc are switching to white/ yellow/ orange nylon tape with a wire filament woven through them. They look similar to packing straps - about 1cm wide or so and can be tightened and even electrifified. They are highly visible to wildlife and humans, cheaply repaired by the simple act of tying broken ends together again (they have a relatively low breaking staring so animals thet are trapped can chew or break free with a bit of effort).
Again though education and maintainence are the real issues here. The parks need many more patrolling rangers and the public needs better awarenes of why off-limits areas should be respected as such. Heavier fines and even monitoring CCTV cameras in high risk (or high preservation value) areas would also help. Solar powered and advertised clearly and widely, also works to ID any potential entangled animals etc. But the NPWS here in Korea, like everywhere, is underfunded and understaffed.
Take care when hiking.
quem deus perdere vult, primus dementat