My phone, an HTC Droid Incredible, may be hopelessly antiquated by the standards of true mobile hipsters. Still, it came with a generous 8GB internal storage. Too bad the SD card is a chintzy 2GB. These days, you get more than 2 gigs on an abacus. It seems like Android wants to use internal storage for the OS and apps, reserving the SD card for media, which makes that 8GB/2GB split a little awkward. I filled that 2GB right up with choice sides of Miles and 'Trane in no time. And, what do I need with 8 gigs worth of apps? What am I running, Bloatpad 2.0? So, anyway, I decided I wanted to use the empty 6 plus gigs on the internal storage for some Thelonious. So, can I do that?
Well, the Help/How to thing at HTC says, "...Music only plays audio files saved on the storage card...". Well, I use another media player anyway - Meridian. Then there's an article called Programmitically accessing internal storage (not SD card) on Verizon HTC Droid Incredible (Android), which says, "To be quite honest, the internal storage is a joke. Just think of it as a flash drive..."
But, it turns out, you can access music and other media on the internal storage. You just have to know that the internal storage is mounted as /emmc. Maybe they shoulda called it /WTF.