The laws are also written with overly complex procedures in overly complex language that generates the need for lots of legal services to implement those laws.
The language isn't particularly complex, it is very precise. Though legal documents do use words that are particular to the field.
The reason such precision is required is that our legal system is "adversarial." That is to say, if you get two sides arguing as best they can, there is a good chance the truth will come out.
The procedures are nothing more than the "rules of the game." If you looked at the rule book for football, you'll see very complex procedures as well.
However, what you may be really saying is why can't it just be "common sense?" The answer, of course, is that "common sense" is more fallible than highly organized procedures.