Why, with the emergence of the state, traditions and customs could no longer ensure order in society and the rulers began to issue laws?

because traditions and customs can control behavior in small groups of people (family, clan, tribe). Moreover, traditions and customs could differ among different tribes. The law is a single set of rules for all residents of the state, which was obligatory for all its residents.

Remember: The process of learning a person lasts a lifetime. The value of the same knowledge for different people may be different, it is determined by their individual characteristics and needs. Therefore, knowledge is always needed at any age and position.