I think 'chaotic' is the technical term. It is technically deterministic, but the system is incomprehensibly complex and sensitive, such that it may as well be

I think 'chaotic' is the technical term. It is technically deterministic, but the system is incomprehensibly complex and sensitive, such that it may as well be non deterministic / pseudorandom. You could drive the same car down the same road at the same time tomorrow, and it may behave differently. It makes bugs / edges cases impossible to reproduce and fix. With a human you can just say "why did you do that? Don't do that." Little fine tuned tweaks to neural nets is not so easy.