Read Section 152 of MTA the description is only a short note and offence is defined in the relevant Section of the Act.
Police need not be in Petrol stations to charge/fine a person for violation of offences stated . If there is a complain from the petrol station to police such a offence can be dealt by police. MTA has lot of offences regarding importation and registration of vehicles and Police are not present when the offences are committed but can be charged if not followed through a complaint.