1. Open source is global, and not everyone is a native speaker of English.
2. Among English speakers, not everyone has the same cultural conventions and nuances. Even within US cities, you can drive 15 minutes, and find very different conventions. And culture in Boston isn't the same as in the Bay Area, isn't the same as in Bolivia.
3. Even within the same culture, not everyone picks up on signals in language to the same degree (whether perceiving or sending). And some people who think they're picking up on signals are conflating with biases more than some others do.
I say I have to remind myself, because this still hits me. For example, when I'm searching certain bug databases, trying to solve an annoying problem, and some prolific volunteer commenting on a bug report there speaks in a manner that comes off as brusque or dismissive. Where they're from (across the Atlantic from me), maybe it's interpreted as professional or capable, and is even reassuring.