@reasoning logic,
If common sense was common, at least in the sphere of human behavior and interactions, then we won't see as many blockheads running around. Everyday in the news, it isn't uncommon to see a story of some individual or a group doing something incredibly stupid and getting in trouble for it.
What is interesting is how some highly educated individuals are seen to lack a general idea of common sense. I kinda see why that is so. With the advent and explosive growth in science over the years, common sense has become an archaic sense to some.
In cause and effect social and economic systems, humans have come a long way from the past, and a level of certainty can be established, especially to the level of accuracy expected from the physical sciences. With that point made, the major application of common sense is largely in the world of human behavior, commonly known to be a very vast in scope with an indiscernible number of variables. Likely why there are people who are extremely educated, but are lacking in the general idea of common sense, and have a hard time creating smooth social interactions.
Common sense is all about making the world sensible, quickly classifying believable information as old news, ignoring counterfactuals, and rejecting explanations that don’t coincide with experience. This perspective makes common sense seem less like a way to understand how the world works, and rather a tool for survival without having an in-depth understanding of the world. Indeed, common sense isn't with its downsides. Once upon a time, common sense propagated the claim that earth was flat, the sun and the stars revolved around earth, as well as many mistakes in medical history swayed by the notions derived from "common sense."