If all the music students were buying their own instruments, or if the instruments were covered by donations, that would be a different story.
But, when the school buys the instruments, it’s expensive.
At the end of the article, the researchers are talking about funding, including funding for musical instruments.
I do agree that sports programs should be separate from the schools, too. Private leagues have teams.
Programs separate from the school system are always the go-to for anyone looking to excel. As far as music, it's normal to get a private teacher outside of the school. Which is fine.