Only newborn diapers have the wetness indicators because the wetness indicator really isn't needed on the larger size diapers once your baby is no longer a newborn.
Newborn's need their diapers changed more often when they wet their diaper and newborns wet more often than toddlers and older babies.
Parents like the wetness indicators on the newborn diapers so they can easily tell when it's time to change a diaper.
With an older baby or toddler they can go longer between diaper changes. And the parents can usually time when they need a diaper change like every 2 to 3 hours is good for changing an older baby or toddlers diaper.