Martialists train for the 10-20% that do.

I think it is admirable for a martial artist or self-defense practitioner to show restraint and avoid confrontations. It is especially admirable for any human being in our society to avoid unnecessary confrontations, instead relying on their one distinct advantage as humans to survive: reason. It is humanity's ability to reason that allows us to survive and prosper.

Conceptually, "situational awareness" is just a name for a specific application of reason for survival. When you see a situation developing -- a couple of apparent ne’er-do-wells glaring at you from across the street with cupidity in their eyes, for example -- reason says, "Avoid this situation.” Bam! Dangerous confrontation thwarted. 

One night you might think, “Do I really need to get a gallon of milk at 10PM when I know that the grocery store parking lot will be dark and rather empty? No, I can wait to get it in the morning or after work.” Just like that, another potentially dangerous situation has been avoided. So many of the fights or confrontations we avoid are preempted simply through our diligent application of that human survival advantage, reason.

Now, with all this talk of reason, with this discussion of avoidance as a virtue, you must remember that some folks are not persuaded by reasoned arguments and are not impressed by your desire to avoid confrontation. These are, of course, people found within the guesstimated 10-20% -- people who rely on the subversive application of their reasoning abilities. That application creates a coercive and parasitic advantage for survival through preying on the weak and the unwary.  

These social predators do not care about your civilized morals or martial ethics because they don’t have any themselves. Instead, they rely on your stringent application of those morals in order to leach their sustenance from you. They are opportunistic, salivating, carnivorous beasts -- some more cunning than you. In their eyes, you are like a caribou in a herd. Unless they know they’ll win, or are particularly hungry, they will not attack the herd of strong bucks and does. They will single out and attack the stragglers, the children, the weak, the elderly, and the unwary.

By themselves or working in packs, predators that see you walking confidently, with strong shoulders and upheld eyes, will tend to pass you over in favor of those whose furtive and fearful glances or distracted mobile phone conversations mark them as tasty, easy prey. It’s one thing to say, “I train in martial arts so that I don’t have to fight,” but don’t delude yourself. These human predators do not care if you have a black belt in System X. They will take you from behind if they know they have an advantage.

Let's say a pack of predators has congregated in a parking lot near your place of work. If you don’t see them and so make the "mistake" of walking to your car, no matter how confident and strong you may appear to be, no matter how much presence you project after all your years of training, it won’t matter. The carnivores will know you can be taken down for that expensive watch you wear, the car you drive, or the contents of your wallet. In such a case, avoidance is not an option. 

When it's do or die time, you must use force to survive and to win. You have tried your best.  You have avoided conflict when you could.  You have not sought out trouble or initiated conflict.  You have, however, been attacked from behind or pushed into a corner. With terrible ferocity and fighting spirit, you must be able to turn in the space of your stride and face your attackers.