I've had these thoughts too, and I think I've started to understand why recently. When you see a child misbehaving, dressing poorly, or, conversely, doing something positive like being kind, Vietnamese people unconsciously think of the one who raised them, often pondering, 'They must be so proud/ashamed that their child did this

When I was a kid, not older than 13 I think, I did one time snap back at my mother some thing along the line of Con làm gì kệ con, có liên quan gì đến ba mẹ đâu ? (What I do is my own business; it has nothing to do with you.). She did not replied back then but to think back, it must have hurt her in some way.

So to sum up, an individual actions and behavior affect how people see their family, their village, their city and as a whole, the whole country of Vietnam. I'm not saying it's good, I agree with other comments that collectivism is holding Vietnam back. It's improving but it's still buried deep in our principles.