People import goods from abroad but do not declare the detail to the authority called

The situation you are describing refers to "smuggling." Smuggling is the act of importing or exporting goods illegally, often to avoid taxes, import duties, or regulations imposed by government authorities. This can involve a variety of products, including controlled substances, electronics, consumer goods, and even wildlife.

Smugglers typically take measures to hide the true nature of their goods from customs or law enforcement agencies. This can include mislabeling items, disguising their true value, or using concealed compartments in vehicles. The consequences of smuggling can be severe, including significant fines, confiscation of goods, and criminal charges. Furthermore, smuggling undermines legitimate businesses and government revenues, as taxes and duties that could be collected are lost. It also poses risks to safety and security, particularly when it involves banned substances or dangerous goods.