- easy to understand and argue
- no room for personal opinion, especially regarding ethics
- less income for crime+punishment system that has a whole industry around it and in some countries even prisons operated as public companies
- emotional views on penal system would go ignored
Precedent law is also highly questionable and dangerous. It's hard to understand why laws do not apply to many, especially those mucking around and making laws.
It could be very simple, but as long as there's no Vulkan (Star Trek) like approach to these things, I'm afraid we'll always have laws that favor some and punish others, regardless if the actions harmed anybody.