There is a real homelessness situation in San Francisco, and it does have some of the effects you describe at least sometimes. The question is its scale. While

There is a real homelessness situation in San Francisco, and it does have some of the effects you describe at least sometimes. The question is its scale. While my experience is now years out of date, I think part of the way this understanding comes about is visitors and tourists are more likely to encounter the homeless people in touristy areas (particularly if they start at Powell St for the cable cars and make the mistake of going southwest, but also in the Haight-Ashbury) while the well-off residents tend to enjoy the city in different ways, and end up in different places than the homeless. Did you ever see the maps of tourist-vs-local photography for San Francisco? There is a huge disparity in the way they interact with the city. The major complaints about homelessness and needles from residents seem to come when the residents are now parents, and there are needles on the playgrounds in any quantity.