It's not an uncommon tactic to give homeless one-way tickets to other cities. In fact, San Francisco actively does it as well [0]. It doesn't seem like San Francisco and cities like it are particularly targeted for this kind of activity. The only case I can recall is in the case of Nevada intentionally sending mental patients to SF which was settled out of court[1].

[0] https://www.theguardian.com/us-news/ng-interactive/2017/dec/...

[0] HN discussion: https://news.ycombinator.com/item?id=18375280

[1] http://www.sfexaminer.com/sf-reaches-400k-settlement-proposa...

I talked to someone who worked at a shelter about this. He was able to provide several cases of someone calling the shelter from another city informing them someone else was on a bus on on their way to SF and that they needed a bed. He had to inform them that a person had to be present that day to request a bed, and the other person on the phone going, "Whatever, they are your city's problem now."

So it does happen, but they don't want to publish it out of fear that it will just legitimize the practice for other cities.