This makes extra work for your helpful, friendly KRF staff because we have to take them out and put them into the non-recyclable trash.
Why? read this: http://www.recyclebank.com/live-green/330-the-pizza-box-recycling-mystery/. If you want the short version, it's because food particles especially those containing fats and oils (aka grease) contaminate the city's recycling equipment.
By the way, the same restrictions apply to:
- otherwise recyclable containers for take-out items from fast-food outlets,
- the plastic and foil liners sometimes used with otherwise recyclable boxes; these you may either place in the regular trash or remove the liners before putting them in the recycling bins.