I have to assume it is about general safety on the streets. Traffic-wise I've never felt unsafe there, but the article's claim about safety is ambiguously worded. It says "Worryingly, nearly a quarter didn't feel safe on San Francisco’s roads at all." But if you look at the question they asked in their infographic, I think people would have answered with general safety in mind more so than just road safety.
As for feeling safe - I used to also feel that most of the neighborhoods are 'fine' (although they seem to increasingly have trash and tents). But then I was physically attacked by a drug addict unexpectedly in broad daylight. And then had friends held up at gunpoint. And now if I ever have to visit SF, I am on high alert and can't turn off being on guard. I feel sad because I used to love SF but now I try to avoid it, both for personal and business tasks.
As for feeling safe - I used to also feel that most of the neighborhoods are 'fine' (although they seem to increasingly have trash and tents). But then I was physically attacked by a drug addict unexpectedly in broad daylight. And then had friends held up at gunpoint. And now if I ever have to visit SF, I am on high alert and can't turn off being on guard. I feel sad because I used to love SF but now I try to avoid it, both for personal and business tasks.