You're taking for granted that your own awareness of modern day guidance systems and exposure to who-knows-how-many sci-fi properties makes recognition of something similar super obvious to you. For someone who doesn't even have a concept of that to understand it in one go is beyond absurd. Also, how could she know that the Predator's system doesn't have alternate modes, for example? If it did, she'd be dead.

And don't go the "realism" copout route. There are reasons why some movies are good and some are bad, and a lot of that has to do with whether or not they make sense.