The scoop on poop

Why are people forced to pick up after their animal goes number two? This seems extremely stupid to me. Who the hell picks up wild animal shit? No one! Seagulls fly around all day long taking dumps on whatever is underneath. It is freaking biodegradable. Farms use it for fertilizing. They harvest crap to shoot through a sprinkler all over their yard. And yet anywhere else we're expected to pick up animal faeces and carry it around in a little plastic bag until one can find a trash can. Until someone is washing my car everytime a bird is flying above me, I will leave my dog's crap on the sidewalk, stranger's front lawn, even on someone's car if the circumstances let be. I refuse to scoop poop.