I use bark mulch extensively in my garden every spring and the birds do indeed fling it about. Every now and then, I have to pick it off the lawn or a nearby plant.
I think it depends on what type of birds are feeding in the area which is perhaps less frequent in public places? I'm no wildlife expert, just guessing.
I have populations of Sparrows, Blackbirds, Blue tits, Ring neck Doves, Thrushes, Magpies and others in my neighbourhood but only the Blackbirds fling stuff around. The Thrushes would probably cause a nuisance if they were more frequent visitors to my garden and I've yet to see a Magpie land (only sit in the trees).