It exists also because legal system is setup that way. For Example I Europe there is tendency to expect more detailed regulation to decide where lines are. In USA you get more general law and then people are supposed to fight it in court. Courts then decide details by cases.

It is rather bug difference.

Also, insurance companies when they settle claims, they force you to formally sue the other person or they sue each other. Most of these are routine formalities. Again, system setup in a way to generate suits.