My comment:
(a) I never ask this question: why "in public"? I also see Americans do this, homeless or not.
(b) I do come to the conclusion that Americans are "efficient" (my word). In both private and public sectors of Taiwan -- as well as its consulate in Boston -- for hours one can hardly find a person to work (because they are sleeping somewhere). In both middle schools and high schools in Taiwan, students are required to sleep for an hour, something I never accomplish. I often lament this custom in Taiwan is a lesser version of Spain, and look at where Spain's economy is heading.