It is from lack of knowledge that the Qur'an was used as a sort of good luck charm. It was used in all sorts of ways, when a child was going to give an exam, when a person was going for an interview, when a bride was being sent with the bridegroom, etc. With knowledge, Alhumdo Lillah such practices are decreasing.
The reason Shias don't do it is because they doubt the Qur'an and give more importance to their 'imam zamin'. So much for lack of knowledge. Brother armughal has said earlier that he has not been to Pakistan and is following Islam, Alhumdo Lillah. He need not be aware of local practices.
Rabbeshrah lee sadree; wa yassirlee amree; yafqahoo qaulee.
Actually I have seen this practice among Shias and haven't noticed it among the sunnis I know... So I think this is something that depends on family customs.