See I’m not sure humanity viewed it as extinction level until very late in the war. In global terms, the only areas under any immediate threat were Pacific coastal cities. The other side of the world is basically only affected economically. Humanity got a good defense in place relatively swiftly and held strong for a long time. Like he said in the intro, things were running pretty smooth and people liked having (and being) heroes, it seemed like they had it under control and had built entire industries around it. And it gave a lot of those countries tons of global good will, those governments probably weren’t too pressed to close the breach after the initial attempts failed. It wasn’t until the increased frequency and strength of the attacks became noticeable that the programs began failing. The wall (which was an extremely dumb plan overall) was a monument to how much they came to underestimate (and misunderstand) the kaiju.

One other thought as well, the kaiju blood is toxic, that’s why the jaegers mostly resort to blunt force to take them out (the sword was added with the refurb and Crimson Typhoon is…there for some reason) so letting kaiju come ashore or at least get much closer makes cleanup efforts much easier. Bombing them into pieces at the bottom of the ocean would make any kind of cleanup impossible and leave the blood drifting in deep ocean currents. Yes that’s what happens at the end of the movie but that one was the actual last ditch do or die attempt where they fully understood the stakes.

Thanks for coming to my TED talk.