Case 1 When Zhang Tao traveled in America , he lived in the home of his American friend , Bill. Once after he had traveled back ,

he found Bill was in a bad mood. When he asked what the problem was , Bill told Zhang Tao that his son Adam got furious about the noise Zhang made when walking upstairs and also because he was using too much water in the solar powered shower and Adam had to have his shower in cold water. Bill told Zhang Tao that he should walk more softly in future , and have a fast shower to save water. Zhang Tao felt uneasy.

How could the host set such rules for his guest?!

Question:

Why did Zhang Tao feel uneasy?