Have you seen wine packed in clear glass bottle. Perhaps you have seen some but its a rare scenario. Most wine are packed in amber glass bottle, either amber brown or amber green.
There are several reasons why wine are packed in amber glass:
1) Amber colored glass hides the true color of wine. Color quality control is a very hard aspect of wine making. Uniform color from batches to batches is hard to maintain. Every production comes in a different color shade. And, bottles of the same production batch may have a different color shade depending on light orientation.
2) Amber colored glass hides insufficient clarification. Try to buy wine packed in clear glass bottle. Examine carefully and you will notice some sediments at glass bottom. Buy again if you fail to see sediments.
3) Amber colored glass prevents the penetration of light that might destroy color pigments and flavors. Just like why all medicine syrup are packed in brown amber bottles, to prevent destruction of potent properties by light.