I think Barbara Ascher is trying to address the possible various reasons that people have to help homeless people. She also makes a point that compassion is a learned behavior not an innate behavior. As she illustrates in her examples, people may support the homeless because of fear. Some people judge others by their appearances and dressing, so when they see people with different dressing than usual they consider them as hurting people and they develop fear. In the first example, the woman gave the man a dollar to get rid of him which is not empathetic. In the second example, the shop owner gave the man food since she felt sympathy for him. Some people understand the sufferings that homeless people go through and want to support them. Compassion
