So it isn't that God is choosing people at random... He chooses people who can and will hear him
Wouldn't it be more impressive if he would communicate to those who are not already worshipping him? Why preach to the converted - this seems like a waste of time if there's a real message to be delivered. If everyone 'heard' a simultaneous and specific message, everyone would be talking about it, know it for what it is and there would be no doubt and no need for faith.