It's just people not knowing the law. The first time I found this site a few years ago I was, I guess you could say "shocked" that you can just carry in the open.
It's not a norm for most people. It wasn't even a norm for a person like me involved in guns and shooting. Society has done a good job pulling the wool over our eyes on our rights, and not everybody notices. All we can do is, just what you did. Carry and inform, respectfully.