Why do you think some people, like those that chose to be members of the kkk, verbally or physically attacked african-americans?

The answer is mention below.

Explanation:

The purpose of the foundation of the Ku Klux Klan, by the former Confederates, was to establish an "invisible Empire in the South". They rejected the reconstruction plan and there were enough evidences of violence against the Blacks and Whites (especially “carpetbaggers” and “scalawags”). They carried an underground campaign against the Republican leaders in the south. One of the examples of Klan activities was in January 1871, 500 masked men attacked the Union county jail and lynched eight black prisoners.

trade regulation is a field of law, often bracketed with antitrust (as in the phrase “antitrust and trade regulation law”), including government regulation of unfair methods of competition and unfair or deceptive business acts or practices. antitrust law is often considered a subset of trade regulation law. franchise and distribution law, consumer protection law, and advertising law are sometimes considered parts of trade regulation law.

in general the theory of economics says that the more open to trade a country is the better   the result for the same country and the whole economies.

in real life countries impose taxes, quotas, etc which is not so good for the economies.

this kind of commercial war between the usa and china is slowing down the growth of the whole world so we can say that it is a draw back of trade regulations. and the free trade agreements are benefits of trade regulations.