because it can decompose quickly if kept in transparent bottles
In Cold countries, the juice bottles are placed under water to avoid freezing.The juice bottles remain in their initial temperature due to the high specific heat of water and it takes a long time for the temperature to fall 0°C.
Silver nitrate is very susceptible to reactions that destroy it, catalyzed by short wavelength light, which is strongly absorbed by brown bottles.
Some solvent or chemicals are sensitive to light, and they get oxidised when they are exposed to it.
The Dicksonia tree fern will have brown fronds if they have frostbite. These fronds should be pruned in early spring before the new fronds sprout.
cause acid has a chemical reaction with metal.
Potassium ferrocynide is stored in dark coloured bottels and kept away from sunlight.This is because it decomposes when exposed to sunlight.Thus it is always stored in amber or brown coloured bottels.
I have kept vinegar in clear PET bottles for over a year and they are doing fine.
There is no need to keep water in colored bottles and many people keep it in clear bottles. Some find colored bottles aesthetically pleasing and choose to use them for that reason.
Perhaps it could be photosensitive?
In soft drinks, besides the carbonated water, high fructose corn syrup (and/or sugar which is better) and coloring, there is usually a flavoring agent, usually kept secret. Especially for the big names like Coke and Pepsi. Any natural or artificial flavorings are kept a secret. I have heard that Dr. Pepper's flavor is prune juice, but cannot verify this.
Because it is unstable after it hit light.