My guess is some may think it unnecessary in the "good area" where they are going to the store, walking, or whatever.Why would anyone carry intermittently?
But... when they go to a "bad area" or area of perceived greater threat then they carry.
That philosophy apparently thinks "bad" people are immobile, you have to go to them.
Or perhaps there is a crystal ball or budding psychic ability that allows them to know the actions of others in advance.
I live in a "good area" but in FL people have cars (or they could steal one) and show up uninvited and unexpected on a little field trip of mayhem in my "good area"; its low odds that might happen on a given day, but if it does I'd rather be carrying than not. So, lacking a crystal ball and psychic ability I just carry whenever I'm dressed and keep a pistol handy otherwise.