Larry: Yes, commas are decimals points and decimal points are commas. If, by context, you can't tell a thousand-fold difference as you did, one maybe should take Backpacking 101, Circuits 101 or Rocket Science 101.
Differences in American English and British English (or is it "English English" or "E^2"?) used to include the meaning of "Billion" and "Trillion", etc. Billion" in the old, pre-1974, British long scale was 1,000,000,000,000 whereas in the USA, Billion in the short scale has always been 1,000,000,000. I still occasionally see usages of the long scale, but it has gotten pretty uncommon and, like its practioneers, dying out.
We'll probably always differ on chips/crisps, fries/chips, cookies/biscuits, biscuits/scones, trunk/boot, hood/bonnet, windshield/windscreen, fender/wing, etc.
Dates: Yeah, the Europeans just do it better than we do. Ascending or descending but not all mixed up. Especially now for sorting computer files, I hope the USA will switch. Like 24 hour clocks for schedules, we're already being introduced to it in transportation and the military.
>"since the US is so bullheaded about keeping its own measurements despite being different from everyone else in the entire world"
Jen: I get your point and agree, but Liberia not only copied aspects of our flag (freed USA slaves took over there in the 19th century) but retains feet, pounds, etc. And then there's Burma. If your country stands against the rest of the world and WITH Liberia and Burma, maybe it's time for a change?!?
>"with "normal" winter temps (not really that cold) in lots of places being a negative number."
Daniel: Ah, but that is true in the Farenheit system as well. At least at my house. I experienced a interesting local usage here in Alaska. Everyone uses "plus" and "minus"/"below" between -10F and +10F), but -15F is just "15" if you're talking about the day's weather because everyone knows pretty closely what the temps are. "It was 13 at my house." "Oh, it was 16 when I got up." can refer to mild or moderate cold. "It was 5 this morning" would be +5F, because -5F would have been called "5 below". That assumption of knowing the temperature within 20 degrees goes away if speaking about past or future or distant events.
An easy solution to the plus/minus is to just use an absolute scale like Kelvin or Rankine. All your expanding gas and infrared emission calculations get much easier than way. "With these 260K temps, the lake ice will be strong by next week." or "We had a great dump on Thursday but then Friday got to 495R and it ruined the snow for skiing."
The UC Berkeley Hiking Club was very heavy in geeks. At a gathering, someone referred to a temperature of -40 and someone else was foolish enough to ask "Celsius or Farenheit?" The mass response of "It doesn't matter!" was deafening.