Notice that the fingers or meter sticks hit different points on the mirror. Extend the straight line of each meter stick behind the mirror and they will all come together at one point. When you look at an image in a mirror, your two eyes and brain use the spreading of the light which has bounced off the mirror as one clue to the location of an image, this clue indicates that the image is behind the mirror. You can stretch strings over or under the mirror parallel to the meter sticks and see where the strings come together. This is the location of the image suggested by the view from two different eyes.
Light travels in straight lines, unless it reflects or refracts.
We have experience seeing an object in air and then reaching out and touching the object. Part of this experience uses our two eye view of the object and relies on our experience based on the fact that light travels from the object to each eye in a straight line. Such a view is incorrect when viewing a fish under water. Anyone standing above a stream who has tried to spear a fish underwater will know that you must learn to account for the bending of the light at the surface of the water or you will mis-estimate the location of, and distance to, the fish. This view is also incorrect when viewing objects in the mirror, light bounces from the surface of the mirror by the law of reflection.