Seems like a great service, it would be a no-brainer for me to sign up if they had a bigger non-fiction selection. Not just business, but foreign language, tech

Seems like a great service, it would be a no-brainer for me to sign up if they had a bigger non-fiction selection. Not just business, but foreign language, tech, science, etc. Maybe they have this already, but I didn't even see a non-fiction category. Am I missing something, and if not are there any good reasons why non-fiction doesn't feature more prominently in the selection?