Carolyn,
People in the US don't see homeless either.  Not that they aren't there. But it is as if they are invisible.  We have them here in Walla Walla.  Did you know that?  Grandad Jack can tell you all about them.  His is a unique view. Many here just think they go away.  Or chose not to think.  That is most likely.  I think your experience in DC is amazing and you can't ever replace it.  I had not even heard of Anacostia til I read about the Bonus March in 1934.  That is where the Shanty town was built. The one that General MacArthur burned. At the orders of the president.  I  was not even aware of where this important event occurred.  How little we think.
Doug