Why is the word AMBULANCE written backwards on ambulances??????

On the front part of most of the ambulances,the word AMBULANCE is usually written backwards as 'ECNALUBMA'.

The reason behind it is that when drivers look behind from their rear view mirror,they find the word ambulance in the correct way and thus they can  provide way for the ambulance.

GIVE WAY TO AMBULANCE..................SAVE LIVES!!!!!!!!!!!!!!!