Another nuance of our idiotic measuring system. Assuming you are in the US, OP. Why are we among the last in the world to actually use the common sense measuring system?

Who was the idiot that decided to divide a foot by 12? And a yard by 3? And a mile by 5,280 (or is it even worse - 5,281?)? Did they come up with that stupid system before math was invented?

It is an industry standard that generally, anything that involves liquids and mentions ounces, means fluid ounces. It gets weird in full scale jets, when they talk about pounds of fuel, especially when liquid pounds don't exist. Consistency is paramount to an intelligent measuring system.