When systems get too complex to simulate from first principles, we have to resort to inductive reasoning--observe the system and then create rules as we see a need.
Yes the resulting rule set is a mess, like our tax code. But the physical system that the U.S. federal tax code (for example) covers--the United States of America--is mind-bogglingly complex.
We have trouble computationally simulating more than a certain number of neurons... there are billions of neurons in each human brain, and there are hundreds of millions of human brains interacting in the U.S. This does not even get into other physical phenomena like surface water or mineral distribution.
The results are stupid because we are too stupid to understand and analyze the system we're trying to describe and manage.