What are reasons the homeless are ignored by society at large in the U.S.?

Nobody (well, almost nobody) knows how they got to be where they are, and most people probably don't really care. We're too busy trying to deal with our own problems. Well, I guess I should speak for myself here. I ride the train to work every morning, and the last train that gets me to work on time is known as "the sleeping train." It's called that because it's the first train to stop by the homeless shelter after they kick everyone out for the day so they can clean up and get everything ready for them to come back the following night. Because most of the homeless people don't get enough sleep in the shelter, they sleep some more on the train. I don't really know much of anything about them, except that they smell bad, they often take up two or three seats with their bags, sometimes they panhandle, and sometimes they behave erratically. One woman started screaming her lungs out, one particular morning, for no apparent reason. They're the people most of us try to avoid, if we can. I have to admit, I try to catch an earlier train, if I can, because that train may or may not get me to work on time.

But then, another morning, I noticed that the transit police were on the train, because there had been so many complaints. One by one, they began kicking anyone who hadn't bought tickets or scanned their card off the train, along with anyone who was being a nuisance. A few times, when the police were escorting someone off the train, I heard them say, "Thank you for your service." At first I didn't know what they were talking about, but then it dawned on me that these people were veterans. Of course, saying that didn't make up for the fact that they were being kicked off the train, to brave the cold weather. One of them gave the policeman the finger while being escorted off the train.

But more disturbing than the fact that these people were veterans who had been reduced to living in shelters or on the street, was when I realized just how little I cared. I just wanted to ride the train in peace and get to work on time. I was annoyed that they kept having to stop and remove more people from the train, at almost every stop, and worried that I was going to be late for work. I was a few minutes late for work, but I didn't get into trouble, so I didn't have nearly as much to worry about as these people did. It bothers me, because I like to think of myself as a kind, caring person. But I guess that's the way it is sometimes. We get so caught up in our own problems, sometimes other people with bigger problems are dismissed as being in the way.