It's a common mistake amongst male martial artists to mistake fighting with self defence. I was thinking more in terms of avoiding unwanted criminal interest, muggers, sexual predators etc that sort for thing. Which is self defence.Are people really that incapable so as to not know how to avoid a fight?
Streets fights are illegal and take place between two (or more) participants, all of whom are willing. The purpose is to defeat their opponent.
If one party is not willing, then it is assault and requires self defence (should it have gotten that far due mostly to a lack of the skills I previously mentioned). Self defence is legal, and the purpose is not to defeat the other person, it is only to create the opportunity to facilitate escape.