I don't know how you'd place some of the tiny surface-mount chips by hand, especially if the neighboring chips weren't already soldered down. Check out the new iPad teardown's photo of the logic board.
Small SMD are tricky to solder by hand, especially when nearby component are so close, but it is not impossible.
Now mounting a BGA without a largely automatic machine would be stupid for high volumes (and even for very small one, and maybe even for unitary prototypes), and in this case it would also be stupid to not pick and place all SMD.
Indeed even with very low wages, it would probably be stupid to mount a board manually except for very low volumes and very small boards. Mouting a small SMD can be done quickly with practice, but you are amazed when you count the amount there is (try on an iphone photo or on a random motherboard)
Now mounting a BGA without a largely automatic machine would be stupid for high volumes (and even for very small one, and maybe even for unitary prototypes), and in this case it would also be stupid to not pick and place all SMD.
Indeed even with very low wages, it would probably be stupid to mount a board manually except for very low volumes and very small boards. Mouting a small SMD can be done quickly with practice, but you are amazed when you count the amount there is (try on an iphone photo or on a random motherboard)