I'm not too surprised, there are not that many people in Cumberland and northern Colchester County and the majority of the population tends to be coastal and therefore does not live close to the highway allignment. As such, the 104 is mostly an interprovincial connector.
The twinning of the 104 is mostly justifiable based on it's status as part of the national highway system and also because of heavy interprovincial truck traffic. Local traffic volumes do not factor into the equation here very much.