National Highways Authority Of India [NHAI] — Toll free access to unauthorized private vehicles

I thought I should write this up as a responsible citizen and hence I am raising the same.
I have witnessed this several times that private vehicles with a sticker/board calling out "POLICE" mainly belonging to junior police personnel having Inspector or below ranks while not on duty getting toll free access through the Vip/Exempted lanes of all the toll plazas across West Bengal(not sure of other states).I find this as a completely unlawful activity.To the best of my understanding and knowledge police personnel on duty and travelling in government owned vehicles can only access the toll free facilities.I request the competent authorities to please take appropriate actions on the same and stop loosing legitimate revenue from toll taxes.