How they government defines homelessness is a big part of this.
For example, a notable number of students in my local area qualify as homeless, though they aren't living the on-the-streets image the word "homeless" conjures. What they are are doing is shuffling back and forth between the houses of aunts, cousins, grandparents and family friends every few days. We used to have a handful of them who would come over to our house once a week and try to carry on a polite conversation with us in their own form of English while waiting for services to start at the church next door. We never could figure out why they decided our house was so great.