Lot's of kids take band class but band class is expensive.
I'm in my late 20s so it's been a little while but in middle school band fees and instrument rentals (if you couldn't afford your own) were like 100-300USD per year. And in high school the cost of participating in the marching band was like 600-800USD (bus rentals, trailer rentals, uniforms, event fees, etc) for a single semester and then concert band was another ~200-300USD for the other semester and the jazz band was a similar ~300ish USD.
And if you can't afford those fees you either just sit in the back of the class doing nothing until you can find a way to make that money or you and/or your parents had to work concessions at the different sports teams games for essentially the entire year to cover the cost. Of course there's only a limited number of slots for that and a single person isn't going to cover that cost in a year, only like half of it. So now to be able to participate in band you depend on your parents being able to afford the energy and time to work in a kitchen or concessions stand for 5-10 hours a week.
And if all the spots are full for concessions and it doesn't look like you'll be able to pay? You get moved out of the band class and assigned to another "elective" course with a lower cost to participate in. All the other ones still of course cost ~150-400USD for the year with the exception of the "learn how to use microsoft office" class and gym. So the poor kids just got sent to those classes and took the them over and over again every year instead of participating in one of the arts classes.
So yes lots of kids take band class. But band class is expensive and it only gets more expensive as costs go up and funding goes down.