No one understands the US measurement system - definitely not the average American. Ask your average person in this country to define an "acre" of land. No one knows. Explain to them that it is the amount of land that can be plowed in one day by a yoke of oxen pulling a wooden plow.
Or, if that is too confusing, it is exactly 660' x 66', or 43,560 square feet. No one knows this. They just know an acre is "a decent amount of land" while two acres is "bigger".
Ask your average American how many cups are in a gallon. Or how many feet in a mile. Or the boiling point of water.
Fortunately, because of international markets they now are selling liquor in the 0.75 liter, 1 liter, 1.75 liter sizes. So much easier. I hope that eventually the US will be dragged kicking and screaming into the metric system. I am old enough to remember when we were close enough to have speed limit signs in both miles per hour and kilometers per hour. But we have too many people here that fear change and are stuck in the "old ways".