Laws are written by lawyers, voted in by politicians (80% of which are/were lawyers), and judged by judges who were lawyers.
Loopholes and vague wording are things that lawyers are GOOD at creating in our system. They are lawyers, they are supposed to be smart enough to make laws very clear; yet wherever you look, laws are written with loopholes and vague wording that permit loads of points of contention to which lawyers must be hired to resolve...
The law tries to be clear, but it never can be because it's fundamentally trying to encode all sorts of fuzzy human emotions/motivations/tendencies, etc.
Let's take your lawyer-free utopia. Rules are crystal clear and the process of checking whether a rule has been followed is straightforward and mechanical. How do you handle something like a fair use rule? A 30 second time limit? What if it's a 35 second clip that's on quietly in the background of an Indie movie? What if it's a 15 second clip of an advertisement lifted directly from a competing company's ad?
Look at laws that have crystal clear applications: statutory rape laws. Did they have sex? If yes, is she under 17? If yes, then guilty! No mind that it was her 18 year old boyfriend. How about drug possession? No need for judges to do the sentencing, we can simply make sentencing mechanical. 10 years for 10 grams, 100 years for 100 grams. No need to consider stuff like that the same amount of LSD can weigh a ton more when it's dissolved in sugar cubes rather than blotter paper.
The criminal justice system is one of those areas where lawyers and judges have been taken out of the loop, with 95% of cases being disposed of quickly through plea bargaining and sentencing being dictated by tables and formulas. It is also one of the most completely messed up, random, and downright unfair areas of the law.