Do you think that the code that tracks loggedin and not loggedin users differs much? I assume is the same tracking code, but if you are not loggedin FB and Google will give you an unique ID but after that they collect same data, they will need to add some code for merging data if they find that 2 different IDs are the same person.

I am not defending FB, my point is that you do not need an army of geniuses to extend the tracking to everyone.