Are you sure? It wouldn’t be difficult for Mitsubishi to add an auto alert if the camera senses something close. Might be worth asking it is makes any noise or not. I’m not suggesting it’d be an optional extra but I know from The Nissan Rogue i rented in the USA it came up red on the screen if you’re too close. I can’t remember specifically if it was making any noise.
"Man is born in freedom, but he soon becomes a slave, in cages of convention, from the cradle, to the grave."