> You're confusing being a jerk with communication styles and cultural differences.
I disagree. We always can simply claim 'it's a cultural difference' as an excuse, but that doesn't make it true and it doesn't make the behavior acceptable. Mature people in every culture look to show respect to others. If someone insulted me and said that, I'd think they were irresponsible and a bit slippery.
I've lived in some of the places you mention, and my experiences don't match your descriptions. People, as they are are everywhere, are generally polite and respectful. They may have some different ways of doing it, but those fundamentals are universal in my experience.
People naturally and quickly divine social norms from those around them.When I travel internationally, I learn and respect the social rules of the places I go. On a sports team, perhaps we pat each other on the butt; I don't do that in an office and say 'it's a cultural difference'. I may kiss familiar women on the cheek to greet them in my culture, but I wouldn't presume to do it in others. Travelers who don't learn the local norms are called "ugly", as in 'the Ugly American". Even entering a new work environment, I learn the social norms; those who don't look incompetent and rude.
How long have the people cited in this thread been in the professional IT culture? If they didn't have their positions of authority and instead had a boss in a company, my guess is that they would very quickly find a way to be polite. My guess is that they are polite with their spouses and kids; their in-laws, etc.