It generally does not. Most human urine is fairly sterile. And even if you've got a bladder or kidney infection, it's the same bacteria that you have on your own skin already -- it infects the urinary tract when forced inside (most often by sex).
Human feces, on the other hand, is quite dangerous. Generally you have to touch it or ingest it to get sick from it, but there are lots of ways for the bacteria to spread.
So the urine isn't dangerous, but if people are urinating in public, there's a risk that they're also defecating in public. And that's more serious.
