Why don't women approach guys they like?

I am not sure if its is culture difference. Where I am from women are not afraid to approach men they like. However in America it is a bit different. From my personal experience, women want the guy to make the first move always. When they see a guy they like, they just stare or try to catch their attention. Most of the time the guys is not paying or attention or notices them.

Why not just walk up and start a conversation. I know people say fear of rejection. However you don’t know until you try. My fiends often tell me women try to catch my attention or stare at me. Unfortunately they choose to tell me after the fact.

For some reason when I was younger things were not like that. I am 27 and back in middle and high school most girls were not afraid or shy to express their feelings for a boy. Not sure what happened. I don’t know if social media has something to it.

What are your opinions? I am from Africa by the way.