Answer, no one really understands 1000 pages of anything. When it gets to court, lawyers will argue for this interpretation or that interpretation, and in the end, a judge decides what the law really means. These overly wordy acts are Congress's way of shirking their Constitutional duty to legislate. The verbose legislation fails to bind anyone to do anything, nothing happens until some judge decides what the law is.
The overly wordy acts occur for a number of reasons, all of them bad. For openers, its hard to get agreement on anything these days, so rather than negotiate, the committee (probably the committee staffers) just puts in everyone's pet language and sends the bill to the floor.
Then everyone on the job is a lawyer. Lawyers get sent to special four year schools that teach how to use a lot of broken English and some Latin mumbo jumbo to make the paperwork unreadable by anyone. Once the paperwork is 1000 pages long and unreadable, they can slip all sorts of goodies (pork) into the nooks and crannies of the law and it will slide right thru Congress.
We ought place a word limit upon acts of Congress. For instance, require that no act of Congress contain more words than the Constitution itself contains. The Constitution has enough words to keep the US of A going over for better than 200 years, that ought to be enough for anything else.