More than steel? We're talking about reusable bottles here, shipped empty. What is the comparison of empty glass or steel to full plastic? What is the difference in mass?

There exist industrial reaction vessels etc which are made of stainless steel with a bonded liner made of glass. That seems like the ideal "forever" food container material to me - chemically nonreactive and easy to clean, but lightweight and resilient to impact. The glass layer would be lost in recycling, but it shouldn't impede recycling the metal too badly as it'd just be a tiny bit more slag in the crucible.

That's a good point. Need to stop subsidizing over the road trucking and build more rail. Much more efficient.