[beebeepka]

Only speculating but something tells me mineral water is often bottled while it's at still hot.

I didn't know what sous vide is. According to the wiki article, containers are either plastic or glass. It boggles the mind. Why would anyone cook in a plastic container

[arthur2e5]

Sous vide is long waterbath at around 55 C or lower. Not a typical plastic safety issue temperature.

Cooking in plastic (or any "original package") has a food safety point in restaurants. Keeping it sealed until the outside is sterilized reduces possible contamination. Immersion also makes for easier and faster heating.

[simmerup]

I imagine because it’s easier. The plastic doesn’t soak up as much of the heat and is easier to shift around and takes up less space