They're not complicated! There's been a tremendous movement over the last 50 years to write the law in plain English and to banish legalese.
Statisticly people representing themself in court have very little chance to win a case.
The sheer amount of data you need to assimilate to just have an idea of what you need to do makes dealing with law a complex matter. Add this complexity to jargon, social and political dynamics and of course, experience, and you have a very complicated problem.
The law is not just an isolated set of words of paper. It's an intricate piece of a several systems.
But you don't need to go this far to prove my point. Take any recent bill, and make your grandma read it, then write a summary of it. She votes, but can she understand it ?
And no law journals, no need of knowledge of precedents. In fact, why even have lawyers?
I might agree that I could read the words in laws and think I understand them, but I disagree that 'the law' is that simple.
Law is like javascript, except every other word needs the same context and explanation that "this" requires.
For example, many reasonable people disagree on whether the second amendment's wording is intended to mean that _everyone_ should be able to bear arms, or whether it's intended to mean _only people in a militia_, and there also seems to be some disagreement on what "arms" means. I can see how a reasonable person could interpret it in either way. Such disagreement seems to have been something which the founders themselves shared.
tl;dr: People disagree both on what we currently interpret words in law to mean, as well as on what the _intent_ was when it was originally written.
And yet, yes, I'll argue that dev, in any language, is complicated.
Hell, there is a good part of the population that will consider assembling an ikea desk complicated. Let's not forget we are in the HN bubble here.
People are fallible. Just because something is simple and known doesn't mean that there won't be mistakes.
Case law, is the only thing that matters.