When is that EVER useful to the layperson?
There is an issue with "kilometer" being a complex word for everyday use (as compared to a mile) in the English language. That's more a linguistic issue that about the unit itself. Other languages have solutions to that with shorter colloquial name for the unit.
Of course the imperial units give a good opportunity for being funny, in ways like specifying speeds in furlongs per fortnight. But you can do the same in SI-derived units, like parsecs per picosecond.
Even in English people of a certain age can say "klicks" and be understood.
Other languages often say just letters "k" or "km".
Really? Do you know how much easier it is to compute surfaces and volumes in metric systems compared to imperial? Concrete example. Figure how much soil you need to buy to fill a box knowing L, W and H. In metric it is a 10s process. In imperial i do not even know how you are supposed to do it. Does anybody even know how many quart are in a cubic foot?
They know it, after they do the conversion, via metric system.
(OK, nowadays you can just enter "1 quart to cubic feet" in Google. And the funnier ones you get at https://en.wikipedia.org/wiki/List_of_humorous_units_of_meas... )
In the metric system, converting between length, volume and weight is trivial and straightforward. This comes into play neatly whenever you need to pile up a precise amount of batter or liquid from containers measured with a different unit.
You say this pretty matter of factly, but I actually vehemently disagree. Many imperial measurements are better than their metric counterparts for day-to-day lay usage.
- Fahrenheit is a better scale than Celsius - Inches, Feet, & Miles are very practical units. Centimeters, and Meters much less so. - Pounds are smaller and offer better delineation than Kilograms. - Liters are pretty similar to quarts, though I admit the various Imperial sub-units are annoying.
Sure, it's easier to convert between metric scales, but the number of times I actually do that?: approximately zero.