[iamnotlarry]

As others have commented here, Japanese relies heavily on inference. Subjects and topics are very commonly dropped.

I shouldn't say that the language relies on inference. Rather, speakers of Japanese rely on inference. It's like chaining functions in some languages.

Car.rent().driveTo(work).park().driveTo(lunch).wash().

By the time you get to the washing in the conversation, the car is hard to find in the sentence, and the driver never does appear. But they are both there if you go looking.