Most of the packaging other than bottles are soiled, often complex (different materials in the same packaging), with variable compositions (several plastics options for the same type of packaging) and available in low quantities.
The environmental balance for the collection, sorting and possible recycling of those packaging is negative relative to incineration with energy recovery (Belgium processes its unsorted household waste by incineration).
It is necessary to provide a simple ongoing sorting message to citizens.
As recycling solutions do not exist for all qualities of plastics, the motivation of citizens would be adversely affected if they learnt that much sorted packaging are not actually recycled.
The additional cost, passed on to the entire system, would be huge and disproportionate relative to the additional quantities recycled