Question

why did the KKK, black codes, and sharecropping fail during the period of Reconstruction?

Answer 1

Democracy also eluded African Americans, who were contending with the oppressive collection of rules known as black codes, until slavery ended in the United States. Widely enacted during the Civil War, a time called Restoration, in the South, these statutes both regulated Black people's rights and used them as a means of labour.
In fact, for the African Americans subjected to the black codes, life after bondage did not vary much from life before bondage. As slavery has become a multi-billion dollar industry, this was by nature, and the former Confederate states found a way to perpetuate this subjugation scheme.

Losing the Civil War meant there was no option for the South except to accept the policies of the Reconstruction-era that ended slavery. However, the one-time Confederacy could hold these newly freed Americans in abstract slavery by manipulating the constitution to deprive African Americans the rights and freedoms that white people enjoyed.
White planters refused Black citizens the right to rent or purchase land in these states and compensated them a pittance. In both cases, the passage of the 13th Amendment in 1865 abolished slavery and servitude "except as a penalty for crime." This clause resulted in Southern states passing black codes to criminalise actions that would make it easier to detain and eventually drive African Americans back into servitude.Not only did the black codes compel African Americans to work for free, they have effectively put them under surveillance. The authorities and elected leaders always supervised their coming and leaving, meetings and worship services. To travel from place to place or to leave town, black people wanted passes and white supporters. Collectively, for African Americans, these laws codified a lifelong underclass status.

Many who were unable to pay their debts threatened gaol or slave labour, as they faced under the black codes. They were deprived of money by the loan peonage scheme and once again trapped into servitude. In comparison, the police incarcerated them, if at all, for minor offences that whites were not punished for in equal amounts. In gaol, free labour was provided by Black Americans, men , women and children.

The black codes may have been abolished, but African Americans continued to face a set of laws that, far into the 20th century, limited them to second-class citizens. It will require civil rights activists' advocacy and the 1964 Civil Rights Act to overturn this law.