This is because rather than improving safety, a mirror can in certain circumstances negatively impact road safety.

This may be due to the following reasons:

• Distortion of reflected image, glare from sunlight or headlamps affecting the driver’s vision.
• Visibility issues during bad weather (rain, snow, and frost), distorting or restricting the view.
• Difficulty judging speed of an approaching vehicle from the mirror image.
• Creating an unreasonable dependence on the mirror.
• The restricted image may also compromise the safety of cyclists who may not appear in the mirror.
• Mirrors can be easily damaged and misaligned.