It doesn't; it just needs to know it was called. You make your selection once it arrives.
Look up the early history of elevators and you'll see a progression from fully manual in-car up/down controls (often with a dedicated human operator); various semi-automatic systems with minor improvements like automatic leveling and door control; and then operatorless systems that started with nondirectional calls:
It is reasonable if you either have low load say a residential building where lift is often idle. Or low number of floors where travel times in either case are short.
