As a process guy, I often hear the term “common sense”. It’s a strange term. Like “luck” it’s a concept that generally brings an end to inquiry, because it’s a reference to magic. “That’s just common sense” seems to be a signal that “I haven’t thought about that, and I’m not prepared to talk about it, either.”
Same with the word “obvious”, sometimes. When you ask a technical question about a product and a developer says that the answer is obvious, you can generally count on that to mean that he hasn’t discussed the matter with anyone. Not discussing it, the team is likely to be oblivious to risks associated with it, if there are any.
It is the tester’s duty to keep an eye on things that seem unimportant, yet might be important after all.
Just because something about a product is obvious to one person, doesn’t mean it’s obvious in the same way to everyone. It may be especially non-obvious to a user.
The obvious leads to the oblivious, and that makes me nervious.