Where are you watching HS football? It sure isn't where I'm watching it. One of the uniforms of my local HS is black jeans and a black and red T-shirt (school colors.) That one is for their community outreach projects - one of which is to be on hand to help out the new incoming freshmen get oriented and find their way around the building.
And just like the males on the football team (or any girl on any other athletic team) they best keep their grades up - or they are gone.
I can only imagine that some schools have more “risque” outfits. Our high school has an extremely conservative looking cheerleading outfit and pom outfits. I watched a game last night... the cheerleaders were very appropriate and downright cute. The cheers were “old fashioned” type... (and this is a public school in a very populated area).
How nice for you.
Are you sure what you describe is the cheerleading team outfit? Or maybe something related? Do they do cartwheels/ jumps/pyramid, etc. at the games in jeans? That doesn’t sound like anything I’ve ever seen on any cheerleading squad.