My reaction to people saying “it’s just common sense” is that the person is acting arrogant, or they have a very dismissive posture for other people. I don’t think I have ever felt it necessary to say it.

I think it’s easy to come up with ideas as to how someone may have never encountered a situation. They’re new to a subject, they have had less professional experience than you, less life experience. Their family comes from somewhere where things work differently. A family member or a coworker has always handled something in their place. If you really felt they should know it, why don’t you involve the person so that you have an opportunity to show off your reasoning, or your knowledge?