Why was the “New South” more a slogan than a reality?
The New South was represented by a diversification of agriculture, away from "king cotton," and the development of new strains of tobacco, primarily burley and brightleaf tobacco. One particular producer in Durham, N.C. produced a burley tobacco package with a bull on the package; hence the name "Bull Durham." Additionally, textiles became a prominent industrial factor in the South although few other industries moved south. The textile industry remained important to the south until the 1970's.
"New South" was more a slogan than a reality because the former leaders of the Old South were also the leaders of the New South. They called themselves "redeemers" as they considered themselves to be the saviors of southern culture. Those more cynical referred to them as "Bourbons," a reference to a statement by Napoleon about the Bourbon Dynasty that they had forgotten nothing from the French Revolution, but also had learned nothing. It was these same leaders who comprised the membership of the Ku Klux Klan. They covered their faces not so much to frighten blacks as to conceal their identity from those who might recognize them.
Additionally, despite the passage of the Fifteenth Amendment, southern leaders went to great lengths to prevent Black Americans from voting. This was done by poll taxes, requirements that one read and explain a portion of the state constitution, and disqualifications for enfranchisement for certain crimes which were presumed to be prevalent in black society--South Carolina for instance denied anyone the right to vote who was guilty of "wife beating."
Furthermore, state laws prohibited blacks and whites from sharing schools, restaurants, and public transportation. The U.S. Supreme Court, in its infinite wisdom, decided in the case of Plessy vs. Ferguson in 1896 that separate facilities were not a violation of the Fourteenth Amendments Equal Protectoin clause as long as they were "equal." From this ill conceived decision, "separate but equal" became the mantra of the South until a later Supreme Court ended it in 1954 with the case of Brown vs. Board of Education.
Thus the New South was a slogan for those who benefited from the "New" mantra, but was in essence the Old South clothed as the New.
Socially, the idea of the "New South" was mostly a slogan. Economically, the slogan was somewhat closer to reality.
Socially, the South did not change much. As soon as Reconstruction ended, it went back to its system of white supremacy. The Jim Crow system was different from slavery, of course, but it did not represent a "New South" that was hugely different from the antebellum one.
Economically, the South did diversify its economy. It did develop some industries. However, the South's economy was still overwhelmingly agrarian. An agricultural economy depending on sharecroppers and other semi-free labor was not that different from the system that had existed before the war.
In these ways, the idea of the "New South" was in large part a slogan rather than a reality.