Final answer:
Items purchased in airport free-trade zones are generally not subject to customs duties if they fall within duty-free allowances. However, exceeding these limits may result in customs duties. Customs regulations like confiscating certain agricultural items help prevent pest and disease introduction.
Step-by-step explanation:
Items bought at a free-trade zone of an airport and then taken into the country are generally not subject to the customs duties of that country. This would be false if referring to items that remain within the traveler's duty-free allowance; however, items that exceed these allowances may indeed incur customs duties. The role of tariffs is to tax imported goods for the purposes of raising revenue and protecting domestic industries by making imported goods more expensive.
The fruit that the backpackers bought at a local market was confiscated by customs because of regulations that prevent the potential introduction of pests and diseases that could harm local agriculture and environments, which is part of the protective reasoning behind customs duties and regulations.