National Highways Authority Of India [NHAI] — Multiple toll plaza within 12 km's

There are 2 toll's in NH66, one at Surthakal and one at Hejamadi. Both are hardly 10 km away from each other. I generally travel from Padubidri to Mangalore which is 30km's and have to pay 135 rs of toll for this. Also there is no single service road which runs along to avoid this toll harassment. At nrmal speed, one can cross the next toll within 15 minutes. NHAI states distance between 2 toll plaza should be 60km's and how come within 12 km's we have to go via 2 toll plaza's?