You're right that people care about convenience rather than caring about DRM - but the DRM affects the convenience. Publishers have handed Amazon a monopsony on a platter, because it's just too inconvenient to buy books somewhere else and put them on a Kindle. And that's all down to DRM.
This is exactly it. No, people don't care about DRM because they don't know what DRM is: but they care about the actual consequences. DRM makes media harder to consume, share (even to yourself) and secure through backups.
