I don't consider being able to lie a Con skill, nor is not screaming obscenities at the Queen an Etiquette skill. Con is knowing the ins and out of how people think to fool them into making the decision you want and believing that decision was their own; like
this. Knowing not to act like a jerk in a biker bar isn't Etiquette, but being able to identify social structure and quantify what the groupings of individuals in a confined space means about their hierarchy is.
Subsequently, having gotten in a fight in high school doesn't give you a 1 in Unarmed combat. Watch an average policeman take down a guy twice his size in less than a second and you'll understand how much Unarmed combat the average person doesn't have.
There is also a difference in knowing how to swim and knowing how to swim properly. Most kids can draw, but they cannot draw on a professional level. Most of them don't even know the basic of contrast on a color wheel.
As far as computers, I'm using a computer right now, but I have no clue how it works. If my computer breaks down, all I can do is turn it off and on again and make sure it's plugged in.
A skill of 1 represents the lowest level of professional training, not the lowest level of competency. Someone with a Con of 1 has had training or professional experience in how to con someone, but they aren't good enough to be a professional at it yet. Think of it like an apprenticeship.
Most basic competency is a default skill.