When US-based companies put things in US measurements and don't provide metric conversions, it makes me (as a non-American) feel like they aren't thinking about their non-US customers. It appears parochial.
Miles I can roughly convert in my head, but I have really no idea what a gallon or a fluid ounce is. I remember a pound is a bit under 500 grams but can't remember how many ounces in a pound. Fahrenheit to Celsius, I know there is a 5/9 and a 32 involved, but I don't remember exactly what to do with them.
What makes it worse here is that the original measurement was in kilometres – kilometres are the standard unit for measuring orbital altitudes in the space industry, even in the US-based space industry – and someone has gone to the trouble of converting that to miles and then omitting to include the original measurement.
The conversion factor is very close to the golden number, so if you just remember the Fibonacci sequence up to around 89 you'll be able to do mental conversions easily enough.
E.g., what's 65mph in kmh? Well, the nearest Fibonacci number to 65 is 55, so 65 == 55 + 10, and the next Fibonacci number to 55 is 89, so 65mph will be 89kmh + ??, now we turn to 10mph and notice it's 8 + 2, so it's really 13kmh + 3kmh, which brings us to 65mph ~= 89kmh + 13kmh + 3kmh = 105kmh. My calculator says the actual conversion of 65mph to kmh is 104.60736, so... that's really close!
This is a very fun little mental exercise to do. Obviously it works in both directions.
Let's apply it to 340mi. The bracketing Fb numbers are 233 and 377. 377 - 340 == 33. Next after 377 is 610, so 377mi ~= 610km. Next after 33 is 55, so 340mi = 377mi - 33mi ~= 610km - 55km = 555km. My calculator says it's 547.17696km. Close!!
I agree with that. Also I used to run road races so I know 10K is 6.2 miles - it also helps because I have a feel for just what 10K means if you follow.
Also - drive around and you more or less know what 100kph is in a car.
But mainly - I understand the point but the reasonable complaining gets mixed up - in a frankly counter-productive way - with political signaling.