Why don't they include the value of used goods bought and sold?

Answer 1

The value of used goods bought and sold is typically excluded from economic measurements like GDP because these transactions do not represent new production. GDP aims to capture the value of newly produced goods and services within a specific timeframe, reflecting current economic activity. Including used goods could lead to double counting, as the original production value would already be accounted for when the items were first sold. Additionally, used goods often do not contribute to current economic growth since their sale does not involve new investment or output.