Glass is heavy, doesn't stack efficiently, sticks/grinds together when stacked, and easily chips and breaks. A full glass container is too heavy to lift safely with one hand and too heavy to carry in a backpack. Glass is slippery, and because it's heavy it is also more likely to be dropped. Drop it on a counter and it cracks or chips, leaving bits of glass in your food and sharp edges that will cut you. The purpose of a container is to _transport_ things; anything breakable like glass is a poor material for something that gets moved around a lot. A plastic container will survive long after a glass container has been chipped.

Glass is fragile, dangerous, heavy, slippery, expensive, loud, and space-wasting.

Plastic containers are light, resilient, durable, portable, compact, and efficient.