The stuff is written down. Just not in the regs! It's in the ACs, or Special Conditions, or Issue Papers, or "industry practice", or any of a million other places.
Part of the problem is that not only are "we" not lawyers, but neither are the people who write the regs - they're largely written by engineers for engineers, certainly on the certification side. (And by pilots for pilots I guess for operational regs). There's lots of places where a basic understanding is assumed in the regs rather than spelled out clearly and unambiguously.
Actually, in some ways I'm happy it's like that; if all it took to understand and apply the regs was basic literacy skills, I'd be likely out of a job!