25 years ago we had to memorize conversions and use a calculator (some calculators included a “cheat sheet”). It was 2 extra steps (convert to metric, do any needed math, convert back) but pretty routine once you got the hang of it.
Since then we’ve had Wolfram Alpha and a ton of unit converter smartphone apps. Even a basic Google query can convert most units.
And yet it’s still more convenient that without Google, I can just go: 1 liter of water is 1 kilogram, 1000ml, and contained by a box of 10 x 10 x 10 centimetres. It will start freezing at 0C° and start boiling at 100C°.
(0.264172 US gallons of water is approximately 2.205 pounds, 33.814 fluid ounces, and contained by a box of approximately 3.937 x 3.937 x 3.937 inches. It will start freezing at 32°F and start boiling at 212°F.)
Yes, everyone knows metric is nicer. But it’s just not an issue at all in day to day life. How often do you need to know the weight of a certain volume of water or the edge length of a cube that exactly contains that much water? For temperatures, everyone memorizes 32 and 212 as a small child and never had to worry about looking it up.
Would I rather use metric? Sure. But when almost everything is labeled in US units, all the advantages of metric pale in comparison to the hassle of having to convert almost every single measurement I encounter.
