I watch people ignore signs everyday also. But you don't really believe all signs hold equal weight. Right? Two signs that MOST people throughout the world tend to pay attention to is a beware of sharks and beware of gators. Stating that is even on the same planet as a stay off grass sign or other non life threatening signs is more than a stretch.
Your wording is a little over the top and makes it seem like anyone who doesn't agree with you is stupid. I'm stating my opinion. A sign is a sign to most people.
One thing I never do is underestimate the average person's stupidity.