Crack has harsher penalties because black leaders asked for them because it was destroying black communities. An example of such a leader is Rep. Charles Rangel (D-NY), who is black and was one of the strongest anti-drug representatives. From his wiki page:
>In 1983, Rangel became chair of the Select Committee on Narcotics, which solidified his position as a leading strategist on this perennially important issue to him Rangel kept the committee going, in the face of the usual pressure to disband special committees. He battled against proposed cutbacks in the federal anti-drug budget, and advocated increased grants to states and cities for better shelters for the homeless. Rangel's amendments providing increased funding for state and local law enforcement were included in the Anti-Drug Abuse Act of 1986. He traveled to countries in Central and South America and elsewhere to inspect the sources of drugs and the law enforcement efforts against them; Ebony magazine termed Rangel "a front-line general in the war against drugs." Rangel said "We need outrage!", making reference to the slow reaction by both government and religious leaders to the epidemics of crack cocaine, heroin, PCP, and other drugs that hit American streets during the 1980s. He believed that legalizing drugs would represent "moral and political suicide". Nor did he refrain from criticizing those most affected by drugs, saying that Hispanic and black teenagers had no sense of self-preservation, and that drug dealers were so stupid that they had to eat in fast-food places because they could not read a menu. By 1988, Rangel was saying that President Ronald Reagan had not done enough in the war on drugs, but that First Lady Nancy Reagan's "Just Say No" campaign had been quite valuable. The narcotics committee itself was termed possibly the most important select committee of its time. The Washington Post said Rangel was "in a powerful position to shape policy on an issue at the top of the nation's agenda". He would remain as chair of the committee through 1993, when it was abolished along with other House select committees.
Rangel is far from the only black leader at the time who wanted harsh penalties for drugs. So while it is true that crack has harsher penalties that other drugs because black people use it, it isn't true that those penalties are because of racist white people. It was destroying black communities, and black leaders wanted a fix, and they thought harsh penalties would work.