Because we can't let poor people have dignity. A large part of our system is designed to punish poor people for being poor, and to make sure that they know it.

I don't think people realize how important hierarchy and order are to the wealthy. As a class, they're so far above basic needs (food, shelter, security) that all that really matters is their station in the world. When you understand that, you'll also understand why the wealthy are almost viscerally, psychotically opposed to anything the "flattens" society: public education, healthcare, social services. They're quite happy to, eg, donate a hospital wing because it's a grand gesture of their magnanimity, but if you ask them to pay the same in taxes they'll kick and scream.

If you just let poor people lead a life of quiet dignity... (shudder)