I agree with all these solutions, and I don't mean to imply that this is an unsurpassable problem, only that our existing security measures for infrastructure are already falling behind as we increasingly rely on them, and these compounding vulnerabilities put pressure on regulators to slow down development.

Yes. Rather famously, the US tested this with a jet smashed directly into a concrete wall, resulting in the video in this article about it. https://interestingengineering.com/crashed-jet-nuclear-react...

I hope that would be the case, but there are other ways to attack infrastructure. Besides physical security vulnerabilities, we have a lot of critical infrastructure that's Internet-connected and running software with known vulnerabilities. Nuclear power plants are some of the most secure in this area, fortunately. There's also the unpatchable problem of the vulnerabilities of the human mind to be swayed by extremists, and young people with career opportunities are constantly targeted. We have procedures in place to protect against these sorts of things, but they are not advancing as fast as our attack surface is increasing, and we rightfully don't want to sacrifice privacy and freedom for security.