I just realized that the phrase "to make friends"cannot be translated literally into German (and French, I think). I wonder if it has to do with the culture. Do Americans actually go out and look out for friends, so they can make some. Do Germans just get to know you and if both parties get along a friendship develops. I asked myself, do we really go out and seek out friends? No, but we do know when we like somebody and then we will maybe put in more effort. Sometimes friendships just develop where you least expect it, so you can try "to make friends"but it is not easy.
So, I guess, it is just an idiomatic phrase "to make friends".
And French and Germans don't make enemies like Americans either :)
Yes, I think many Americans do purposely go out to "make friends". As an example, one of my favorite restaurants has a "community table" at which anyone may sit. So, if you're on your own for dinner, you can sit there and still have company. My wife and I will sit there when we're in the mood to meet new people. Will these people really become our friends? Probably not, but we'll certainly never know if we don't actually have a chance to meet them in the first place.