I do engineering for government contracts. The spec for the system I work on covers thousands of pages. I've read about 6" thick worth of it and that is less than 10%. But they detail down to the most minute thing what you are allowed to do and not allowed to do. The big picture stuff fits on the first 10 pages, and then they drill down into exactly what kind of thread you can have on a fastener and exactly how you are allowed to stress a weld for the next 1,000 pages. But it stems from previous experiences and errors, and it leads to a better product (though a more expensive one).
So I don't think "# of pages" should ever be a metric for judging a law.