No. Dressing yourself to suit the situation is a normal facet of human society in pretty much every culture on the planet - how could this possibly be an alien concept to you?
Because no one does it here.
And your parents never had you dress up for anything when you were a child? Pu-lease. You've been in the United States for your entire life so don't try to give me a bulls**t answer - you've seen people dress up for certain occasions, and you've more than likely experienced it in your lifetime. Just tell the truth already - the concept is not alien to you, you just don't like it.