They care about privacy... but they care about staying in business more.† They are in the business of providing web services (i.e., things you ask their servers to do to your data.) If they can't do anything with your files besides store them, they don't have a business.

† (To assume otherwise would be odd, wouldn't it? It's like taking someone saying "I like ice-cream" to mean "I would allow you to shoot me in exchange for some ice-cream." We assume people have an implicit preference for staying living. We should probably assume companies do too.)