If recycling is the priority, in an ideal world, everything would be made of the most recyclable material, and only that one. A simplistic way to look at it would be to say that the difficulty of recycling any kind of packaging increases proportionally to the number of materials used to make it.
Easy to recycle?
In reality, we find food and beverage packaging of all kinds – for several different reasons. The primary purpose of packaging is to ensure the integrity of the product it contains. Consumer health and safety are the next priority. Different packaging types are appropriate for different products, in different forms (warm vs. cold, for example).
Marketing also plays a key role in determining the kind of packaging used. Consumers might prefer transparent packaging because it allows them to view a product or they might prefer a material that seems more natural.
If we want to be able to recycle more, recyclability needs to be introduced in the packaging design considerations hierarchy. The first responsibility of packaging will always be product integrity and consumer safety. But simpler products are easier to collect separately (including by automated machines, such as smart bins) and to recycle. Once consumers understand that, it could also be the best form of marketing.