I've heard that tetrapak are like the worst type of material to recycle.

IIRC they're a combo of paper, aluminum foil, and a plastic inner coating. Individually, the paper and aluminum are relatively easily recyclable, but I recall seeing somewhere that because it's all bound into a single material, the labor/energy cost to separate the layers of tetrapak for recycling end up not worth it and it just ends up in landfills...