Why is the USA the only country who doesn’t use the metric system?

USA uses both, just like the UK and Canada. It’s standard in the states for…medicine, the military, science, and… two-liter beverage bottles.

Soft drinks in general. A can is 255ml, a bottle is 500ml, a big bottle is 2L

Convenience store wise, a can of Coke is 12 ounces and a bottle is 20 ounces in the states. They have the volume in ml on the bottle though.

Grocery stores have 1l, 16.9oz, 12oz bottles, and 7.5oz cans.

It’s all over the map.

Containers of Specific Volumes For industry.