It is said that classical music is inaccessible to low-income citizens based on concert ticket pricing, but what is said about its accessibility to study it?
Here you will find information on what is needed to get into some well known institutions (I am using piano majors to unify this example)
New England Conservatory: http://necmusic.edu/apply-nec/audition/piano
Eastman School of Music: http://www.esm.rochester.edu/apply/aud_rep.php#piano
Oberlin Conservatory: http://new.oberlin.edu/conservatory/admissions/auditions/keyboard.dot
To sum it up, you need to have certain skills before these colleges take a second look at your application. Most people aren't born with these skills, and therefore have to learn them from a teacher. With years and years of study, one can get these skills.
Lets look at how much this education could cost. 5 years, $30 a lesson, one lesson a week. With 52 weeks in a year, that comes to $7,800. Now imagine if I used a number that actually approximates the actual price of a lesson.
It is simply not possible for a person interested, but not educated in music, to decide to attend music school half way through senior year of high school. You need years worth of skills and the money to pay for them. A public school student with good grades and various math / science courses under his/her belt has a fair shot at engineering school. The math / science courses needed to get into engineering school are provided by the public school, the music education is not.
We, the lucky ones, owe so much to our parents. They gave us the option to choose music school. Unfortunately, not all parents posses the resources needed to provide such options.
At the very least, early education must provide every student the option to move on to higher education, in all fields, free of preliminary costs. Hard work is the only thing it should take to get in.