They have a plastic lining to stop the soda from tasting like metal.

They need a liner on the inside mostly epoxy or polymer.

Glass because the added weight ends up being less eco-friendly than plastics during transport. So it’s better to only get glass from local distributers. Also the recycling process of glass is fairly eco unfriendly too.

Aluminum cans might be the best we have for now. I have seen paper milk carton style containers come up more often. As well as plant based plastics.