It bothers the heck out of me. If you don't understand why rules such as these are established then find out more before choosing to make trouble. I find that people who do this either genuinely don't understand or think that those who enforce the rules are overreacting.
Yes, this sure does bother me as it was once explained to me by a wild life officer that ducks etc can get very sick from bread, and things that humans feed them.
I do not know why people cannot read signs and it upsets me to see this happen -I have sometimes gone up to the person (when I lived opposite a huge lake and walked every morning) and pointed out the sign to them.
They do not like this generally!
Yes, It does annoy me! The signs are there for a reason. Last time my husband & I were sitting on a bench at Circle Quay, a man in front of us on another bench was feeding crumbs to seagulls. (A lot of (bread) crumbs!)