Shoe sizes vary around the world for several reasons, including historical, cultural, and practical factors.
One reason is that different regions have different customary units of measurement. For example, the United States and United Kingdom use different measurement systems for shoes, with the US using a numerical scale and the UK using a combination of letters and numbers. Other countries may use the metric system or other variations.
Another factor is that foot shapes and sizes vary among different populations. For example, people of Asian descent tend to have smaller and narrower feet than people of European descent, and this can affect the sizing of shoes produced for those markets.
Additionally, different brands and manufacturers may use their own sizing systems, which can further complicate the issue of standardization. In some cases, brands may even use different sizing systems for different models of shoes.
Overall, the differences in shoe sizes around the world are a reflection of the diverse cultural and historical influences on the development of footwear and the variations in foot shapes and sizes among different populations.