Color coded holidays

Today is St. Patricks' day holiday and once again I am reminded of Americans' curious way of color-coding all holidays. I am guessing it is an American thing, because it seems to be too bizarre to be, say, European culture. Every American holiday has a color associated with it - Christmas is red and green, Hanukkah is Blue and Silver, St. Patrick's day is green, etc. You can tell what holiday is approaching just by looking at the color of decor in a shop window. It is as if the Bible gives specs for the HSV value of the exact green to be used because the Christmas green is very different from the the ST. Patrick's day green! I am a Hindu and given our pantheon of Gods, we can celebrate a holiday almost every week of the year if we like, so I understand holiday symbols and icons but I don't get the colors. I am guessing the color-schemes were introduced and promoted by the marketplace to induce people to change their home decor and such with each approaching holiday, and sell more products as a result, but it is even more curious how whole-heartedly the colors have been embraced by everyone. It could be that because most American have long been removed from the native culture these holidays originated in, they do need specific colors and icons to celebrate the holiday. Just as unable to be completely submerged in the Diwali atmosphere, I chooses a few icons and rituals to celebrate it. To my kids Diwali probably means nothing more than those few icons, and will eventually celebrate Hindu holidays in the same way signified only by a certain color, food or icon.