Because they are ashamed of them.
I must explain. The discovery of unconscious mind was one of the breakthroughs of the science of psychology. But we now are in a decidedly anti-scientific mood. Science was fine as long as it made us rich – but was not acceptable when it told us things about the world we did not want to hear about. That our brief period of success was over.
The unconscious is a storage place for most of our social learning – the repository of our culture. We cannot function without it – because it helps us to react quickly, in response to the many sensations we receive from our world. This is where we learn our language – as small children, when we learn almost everything we know.
As adults, our behavior is based mostly in this early learning – where we learned how to be. Unlearning this early learning is very difficult – and we usually don’t even try.
Discovering what is buried in our unconscious is not easy – because as 20th Century people, the world over – we have used it to store beliefs we don’t want to know about. But which form the basis of many of our actions.
We do many bad things – but usually project them onto others. And this gets us into a lot of trouble – into wars against the evil ones – often labeled as terrorists. We love going to war – and will sometimes do so at the slightest provocation.
This is destructive, war by its very nature is destructive – and we realized this by ruling out Industrial War, after WWII – and limiting ourselves to wars in undeveloped countries. This was an improvement – but still devastates large parts of the world – resulting in millions of refugees. Americans deny their involvement in this – when nothing could be more obvious.
Let me return to the shame Americans feel about their unconsciously-motivated behavior. They have destroyed the most powerful nation in history. Not the nicest nation – the Ugly American was legendary – but the most powerful economically.
Americans will say “But we did not intend (consciously) to do this – to impoverish ourselves!”
But this hardly matters – the net results speak for themselves.