Why Does it Take Most People So Long to Learn How to Read Music?

The answer?
Following the Traditional Route.

The "normal" methods used to learn to read music still rely on techniques that were first devised over 200 years ago! Interestingly, most every other discipline has dramatically improved its learning techniques.
Science, for example, was once completely learned by book. Of course now, almost all science classes have a "lab" portion that teaches you to use the information you just learned.
Traditional methods of teaching to read music almost exclusively rely on some sort of "homework" like drawing notes for the application portion of the class. And while this might work great if your goal is to sight read one note at a time, it will leave you helplessly stranded if you want to read musical "phrases" (which is by the way how every one of world's greatest musicians reads).
If you think of the greatest musician you know of; the one who can literally sit down and play almost any piece you set in front of him or her, they read line by line, NOT note by note. And EVERY book, manual, class or flashcard program teaches you to read note by note.
Fortunately, a few "rebel" musicians have recently begun dissecting traditional music education and have discovered several dramatic short cuts that can help even beginners learn to read music 2,5, in some cases even 10 times faster than the traditional method!
Their findings will be published in several weeks, so keep a watchful eye and ear. And if you're serious about wanting to learn how to read music, don't choose a program, system or class until you read there discoveries.