"Why...?" He tilted his head a good few degrees, like maybe that was a strange question. "Um... because it's kinda heavy?" He looked down to the garbage can full of metal and plastic. "I guess I could roll it on its edge instead...."

To illustrate, he reached back over to it and tilted it, then did exactly as suggested, treating it a bit like a wheel for a few feet, before settling it back down again. "...Does it matter?"