What about iCloud? Wouldn't they be liable for every song, every photo, every video, every document their users store? Maybe they've got songs (mostly) covered

What about iCloud? Wouldn't they be liable for every song, every photo, every video, every document their users store? Maybe they've got songs (mostly) covered via the agreements for iTunes Match, but the rest seem hard to pull off (especially since, IIRC, taking a picture (or video) of a copyrighted painting, sculpture, etc. can be infringement in some cases).