HN is not an exception. It's the most stark in threads about salaries.
The thread seems overly negative towards Americans and criticizes them heavily because half of America is still asleep and the other half just started working. If OP posted it later Americans would likely be filling the discussion with the reasons why your complaints are happening.
My personal opinion is that US-centrism is obviously a thing, but EU people are so used to seeing it that they then mistake other things for it.
This same thing happens with Spain and Mexico as well!
I'm not talking about currencies. I'm talking about sentences like "if you move to the east, you'll earn...", "in the south, it's..." in conversations with no prior indication that it's just about US and "the east" means "the east of US" and "the south" means "the south of US". Because US is the whole world and there is no need to clarify...