What are the in-universe reasons for the initial faith in the Anti-Kaiju Wall?
This question has bothered me ever since I saw the film many months ago. I realise that it's a spectacle / monster-mecha slash, and I am usually very quick to gloss over holes, but this one really stuck with me for my complete inability to comprehend it.
If I understand correctly, support for the wall rested on these items:
- No Kaiju would attack a wall bordering the coastline. The film doesn't seem to give an explanation for why this is considered a viable assumption. While there may be some merit in observing that wild creatures don't attack walls, it feels too flimsy to build a population's survival on.
- Building and maintaining the wall would cost less than maintaining a fleet of Jaeger. Building a Jaeger is costly, in the order of a hundred billion dollars, but I hesitate to think of the cost of a wall that shields off, at a minimum, every mile of populated coast bordering the Pacific.
- The Jaegers wouldn't last forever. Recent setbacks/losses among the Jaeger led people to think of an alternative for the long term.
However, the drawbacks seem grave enough to sink the plan immediately:
- What happens when the wall is breached? Is there a contingency plan?
- It's hard to overstate just how much coast borders the Pacific; tens of thousands of kilometers.
- Seeing the wall in the film left me intensely skeptical that it would stop creatures of the size mentioned. Kaiju could probably have just climbed over.
- I recall turrets being mounted on the wall, but pre-Jaeger history taught that kaiju required up to several nuclear strikes to kill. What are we going to load into those turrets?
Obviously, with the benefit of hindsight, it didn't work out. What I'm curious about is what made the Pacific Alliance sign off on the idea as a replacement for the Jaeger? What did they realistically expect the wall to accomplish? Are there in-universe reasons or benefits that I have overlooked or am unaware of?
Note: I've only seen the film, not read any novels, but any canon, in-universe reasons will do.
Anti-Kaiju Wall — Wiki Pacific Rim: "The assumption that no Kaiju would attack a wall bordering the coastline was the primary backing for the idea behind supporting the wall over the Jaeger Program."
Jaeger — Wiki Pacific Rim: "Unfortunately, the development of the Jaeger program has not come cheaply. The cost of building the Mark-5 Jaeger Striker Eureka, for example, was reputed to be over a hundred billion dollars, more than ten times the cost of a nuclear aircraft carrier."
Anti-Kaiju Wall — Wiki Pacific Rim: "The belief that the Jaeger Program would benefit the world in the long run was thought to be a hypothesis without a strong basis."
Film snippet: "Breaking News: [...] Alliance in support of the Wall of Life program clearly stated that the constructions would withstand [...] highest category [...]"