When you are approaching a strange girl, whatever your intentions may be, any person watching, or the girl herself, really does not know what your intentions are. They cannot know if you are interested in getting her to bed. Not for sure anyhow. You can make your intentions known to the girl when you choose.

This takes a lot of pressure off of you. You are not appearing in public, proclaiming to everyone that you are out looking for sex. You are simply a friendly, courteous individual saying "Hello" to a girl.