I thought the spring-loaded cover over the waste bin was to help mitigate any potential fires. It would deplete the waste receptacle of oxygen to help snuff out the fire and aren't the bins also rigged with their own, automatic fire extinguisher sprays inside?

On Singapore Airlines, they have a nifty little floor pedal that you step on to open the receptacle. You drop in your waste, take your foot off the pedal, and it snaps shut. How civilized!