I dont think it should be "instead". Suggesting that emergency brakes are inadequate due to one passenger failing to locate one is kinda cheap.
We could also easily construe your argument as "engineers would never design a flaw", which is demonstrably untrue. We should both work to minimize errors, and to provide a variety of corrective measures in case they happen.
We could also easily construe your argument as "engineers would never design a flaw", which is demonstrably untrue. We should both work to minimize errors, and to provide a variety of corrective measures in case they happen.