The South's low number of urban areas resulted in a low instance of banking, finance, and law-related professions.
The South became devoted largely to agriculture, and especially to plantation-style farming. The lack of urban centers was not specifically the cause of a slave economy developing in the South. But it is the case that the plantation economy led to less development of some other professions and institutions that tend to be associated with industries and cities.
The weak position of banking and financial institutions in the South was further weakened by the Civil War. Banking was devastated in the South by the time the war was done. Confederate currency had become essentially worthless. Their whole system of finances needed to be reconstructed during the Reconstruction era.