I think the defining factor in the abovementioned scenarios is a difference in culture.
In America, blacks have their own separate culture, though most function in both their culture and the culture at large. White folks in general don't understand this. In fact, I'll admit that I didn't understand this until I attended a Historically Black University.
A great example in general, and a good model for cross cultural understanding came at a Masters class in Education I attended this past year. The instructor was black and taught in an urban school district filled with minorities. The thing about Maryland is that you cross the Chesapeake and you are in a rural predominantly white area. She came over to our area to teach this class and every single student was white.
After touching on the subject in general, she asked a question. "Why did a white teacher get upset at me after I chastised her unruly class in the hallway? In black culture, it takes a village to raise a child and that means every adult should pitch in to correct misbehavior."
'Well, that teacher felt like you were intimating that she couldnt handle her own class. She felt like you just insulted her and undermined her authority," we told her.
You can see the effect of the dominant individualistic culture. Funny, we all knew exactly how that teacher felt. The instructor took that in and said, "Hmm, I never would've thought of it that way, but I see it now. So, if the tables were turned and it was my class that was unruly in the hallway, what would you do?"
' Well, we would feel bad that you wouldn't be being successful with your classroom management, but discretion being the better part of valor, we would vow to keep quiet about it so you wouldn't get in trouble.Especially since we really like you.'
"WOW!" she exclaimed, "I just thought the white teachers were unfriendly, not team players and possibly racist."
The wheels in her mind turning, "What if you knew that I would appreciate a helping hand with my class at any time?"
'Then we would definitely help!
You see how that scenario was about communication? Miscommunication and lost opportunities because racial subjects are so charged with emotion in America?
The class learned a lot that day and so did that instructor!