Girls are afraid to take the first step, they are often shy of taking the initiative so as not to seem Intrusive, and the guys are frightened of being rejected and as a result the feeling of self-depreciatory and underestimating of themselves.
Sometimes when starting communication or meeting a new person it is not immediately possible to understand if he/she is interesting, clever, witty, and if he/she is an appropriate person for you.
A beautiful girl can appear not as intelligent as you wanted to believe or simply bitchy, and a handsome guy may be boring strange or unpleasant.
And the girls don't want to impose relations to the guy; everyone wants the communication and acquaintance to start without any efforts, freely.
Social networking has not much solved this problem, because people communicating there are mostly familiar to one another. If you found someone in the chat, it means the other person is ready to communicate and get acquainted.
Sometimes on the very first date, having learned a person better, you want to turn around and run away.