Is Concert Dress Code Class Discriminatory?

I'm still in a band frame of mind right now, so I'll discuss something that happened this past Sunday that made me think of class in a context I hadn't considered before. I was prepping the stage before our concert this past Sunday and got a text message from one of my friends in the band saying he didn't have the all-black attire that was the dress code for the concert, and asked if he could wear something else. I said the answer was no, and that it would be better if he borrowed a friend's clothes to use for the day. After the concert, he remarked that he didn't have the money to spend on a set of clothes that he would only use once. I realized I hadn't been thinking about concert dress that way before, but in retrospect it does seem like an aspect that is unintentionally exclusionary toward people with less spending money to throw around.

I've been playing in school bands for the past ten years, and not once have I encountered a person who wasn't able to pull together the necessary articles of clothing in time for the concert. The policy of every single conductor I've had was that if you weren't in concert dress on the day of the concert, you couldn't perform. Does this mean that school bands are class exclusive, dissuading people who are not of the appropriate social class from joining in the first place? If there are students struggling to make ends meet financially, and can't spend money on concert dress or music lessons, do they even consider joining a band an option? You don't need money to join in the first place, but you do need it if you want to continue for a significant period of time, or progress to a level where it no longer becomes necessary (unless you have friends or family who are willing to provide the resources necessary in lieu of any money being spent). Maybe this isn't the case, and it isn't a significant obstacle, but it certainly seems like it might be; being a part of a band might be another component of the middle class education framework designed to exclude those who don't fit the mold.