Numbers are scarce, but experts agree the data that does exist probably vastly undercounts instances of abuse across China. The country’s courts dealt with 11,519 cases involving child molestation from the beginning of 2015 to November 2018, according to Xinhua, the state’s official news agency.

Shang Xiaoyuan, the director of the family and child research center of Beijing Normal University and a director of the Child Welfare Protection Council of China, said studies had estimated that 1 percent of all Chinese children were raped and that many times more were put in sexual contact with adults. Girls’ Protection, a Chinese public welfare group, said in its most recent report that the cases made public were “only the tip of the iceberg.”

Over the past two decades, hundreds of millions of people — a group almost as large as the population of the United States — have moved from the Chinese countryside to its crowded cities to seek their fortunes. Tens of millions of children have been left behind in rural areas, often with limited care.

In that environment, the sexual abuse of children has proved hard to control, said Professor Shang. “It’s like a disease which can happen anywhere,” she said.

Chinese officials have vowed to step up enforcement. China’s law enforcement agencies and courts changed their procedures in 2013 to make it easier to prosecute sexual abuse of children under age 12 and ordered severe punishment, particularly when there was an organized effort to procure children for sexual abuse. Last year, China’s top prosecutors recommended a further crackdown on sexual abuse of children.

The usual penalty for child molestation in China is less than five years in prison, said Zhou Hao, a lawyer in Beijing. But if other charges are also leveled, the term could be five to 15 years, he said.

The reports regarding Mr. Wang have led to a wave of online anger in China. That anger intensified after the initial decision of government censors to block online discussions and media reporting of the case. That decision, quickly reversed under public pressure, has raised the question of whether the government is too quick to protect wealthy and well-connected citizens even when they are accused of criminal misconduct. Some Chinese media outlets over the past few days have called sexual abuse of children a national problem, though the instances they have cited mainly involved educators at elementary schools.