Lol! Peebs wake up! It costs Farnells, Digikey etc Big money to dispose of it's waste. Courier costs are bulk paid and so individual items are not an issue. By off loading it's packaging on to you they save in two ways
1. They save on repackaging
2. They save on disposal costs
They are simply shuffling their waste problem on to you. Even if the item is 'recyclable' the actual admin costs far outway the monetary returns. What will you do with the plastic tray? exactly bin it. Then it goes to landfill at NO cost to them. Parcel it up and send it back, at least that way it's their problem once more.