Why can't everything be recycled?

Not everything can be recycled due to several factors, including material composition, contamination, and economic viability. Some materials, like certain plastics, may not have recycling processes available or are too complex to separate and process efficiently. Additionally, contamination from food waste or other substances can render recyclable materials non-recyclable. Finally, the cost of recycling certain items may outweigh the benefits, leading to limited recycling options for those materials.