The difference is that glass bottles were consigned and re-used. Also energy use does not tell the whole story and one should consider the impact of plastic tha

The difference is that glass bottles were consigned and re-used. Also energy use does not tell the whole story and one should consider the impact of plastic that is not recycled or worse, left adrift in the sea or in our rivers. You make a good point and it can be interesting to know how many use of a bottle are required until it becomes more energy-efficient compared to disposable plastic, etc. The shift to the all plastic packaging paradigm was made when companies found out that they could simply let the consumers deal with the packaging once the product was consumed instead of having to get it back from their hands and process it. Hence the modern plastic dystopia.