Why is the customary system not popular all around the world?

The customary system, primarily used in the United States, is not popular worldwide due to its lack of standardization and complexity compared to the metric system. The metric system is based on units that are easier to convert and understand, making it more efficient for scientific, educational, and international contexts. Additionally, most countries have adopted the metric system for trade, commerce, and education, promoting global consistency. This widespread adoption has rendered the customary system less practical and useful in a globalized world.