Are `meter` and `metre` pronounced differently?
> It's an extra kicker that people who don't use metric units also get to change the spelling of metric units the rest of us are using.
Assuming you are referring to the US, we use metric. We just don't use it for everything.
What a strange high-horse you sit on.
I wouldn't imagine so.
Bit like how cheque and check aren't pronounced differently -- so not really homonyms, as the meaning is the same (or at least in the North American interpretation usage, one of the meanings matches the meanings of the standard English word / spelling).
In English, meter is a device used to measure something, and it's convenient to distinguish that by spelling (rather than relying on potentially ambiguous context) from the SI unit for length -- the metre.
Similarly, a thousand x 1kg (SI unit for mass) gives you a tonne -- this is also easily distinguished from the myriad variations of 'ton' that may refer to mass or volume (eg UK, US, long, short, harbour). Seeing US publications regularly use the phrase 'a metric ton' provokes a similar reaction of despair for my horse.