How can this happen?!

I was in Hong Kong awhile back and each time I go off to Temple Street or the MongKok area, I see this happening. And I just can't understand how someone could do this to another human being.

These people will leave a handicap person on the street and put a bag for money collection. At the end of the day they come and pickup this person and the money.

Here I've got a picture (taken Oct 10, 2007) and he is lying there and people are walking around him.