Indeed street fights are nothing to fear, usually.
Yes, they are, no matter in what country you get attacked. That's because you never know what the attacker does to you when you get KOed. And you never know whether you fall unlucky when the attacker just pushes you, so that you hit your head on concrete.
Therefore, talking about self defense and pride aside, every fight should be avoided and every attack has to be stopped before you get hurt. Again, I'm not talking about revenge and I'm not talking about over-reacting, but you have to do what it at least necessary - which depends on the situation and circumstances. If there is an attacker with a knife, I wouldn't recommend counting on to keep the margin between "what is necessary to stop the attack" and "getting hurt" too small as you don't know what the attacker is able to do.