<s>[INST] Why has the world not yet agreed upon using one set of units (i.e. meters for distances and kilograms for weight) everywhere? [/INST] The most obvious reason is history. When you have used a system for as long as anyone can remember, a different system will seem strange and probably even wrong.
Also if e.g. gallon should change to Liter that would make the prices rather hard to comprehend, - at least for a while.
Also there is pride. Our system is better than your system.

But there is some movement and e.g. NASA is using the SI-system (meter for distance etc.) in most projects.</s>\ <s>[INST] But wouldn't unifying the SI be globally beneficial? [/INST] Yes, unifying the SI system would likely have many benefits globally. Some of the benefits of a unified system include:

Consistency: A unified system would ensure consistent units of measure across the world, reducing the risk of misinterpretation and improving accuracy.

Simplicity: A single system would simplify measurements, making them easier to understand and use.

Interoperability: A unified system would make it easier for countries to communicate and exchange data, improving global collaboration and cooperation.

International trade: A unified system would simplify international trade, making it easier to compare prices and products across borders.

Better science: A unified system would allow for more accurate and precise scientific research, leading to more advanced technologies and innovations.

However, it's important to note that changing a long-standing system is not without challenges, and the transition would likely require significant effort and resources from countries around the world.</s>