The phenomenon of the left side appearing right side and the right side appearing left side on reflection in a plane mirror is called lateral inversion
It flips photos around from left to right.
Because we can adequately align the proper alignment of the image, the characters in the ambulance are written laterally reversed.
Analyzing lateral inversion:
Take a look at the picture created by the plane mirror. You can see your reflection when you stand in front of a mirror.
Our left appears to be right and our right appears to be left in this reflection. Lateral Inversion is the term for this phenomenon.
Also, if the laterally inverted text is written on a piece of paper and read from behind, it appears upright, even though it is still reversed because it is a mirror image, but letters may now be recognized.
Lateral inversion is the term for this front-to-back reversal.