I’m going to have to say that Southern states pay more because the income of southerns are in low wage.
For example, other countries that wanted higher control of various regions started investing in other aspects of warfare such as aircraft building which was not covered in the conference. Japan for example started annexing territory in order to ensure greater control over the Pacific region which was also not forbidden by the conference.
I believe the answer is "change to meet the needs of a modern society".
