There's a basis of belief in Western culture, that is 'original sin'. So it might be very natural for them to feel humans are imperfect in a country where almost all people are Christians.

Obviously this idea is totally unfamiliar in traditional East-Asian culture. If we were born under no particular defects both in body and mind, of course we were born perfect. Here imperfect means handicapped, disabled or subnormal.

Aside from that, I agree humans make mistakes. But I must say this is a sign of human evolution. It's not human that is to blame, but a system. Human makes an error because existing system won't have been able to follow the speed of human evolution.