Well its not so much that learning to learn is more difficult, but learning to learn in a given domain. If you don't have someone to teach you, figuring out the ideal way to learn something can be tricky.

For example, the Rubiks Cube. I'm sure there are great ways to learn to solve this puzzle, but I learned using a very time consuming technique with a lot of failure. While I have a really good schema for book learning, I have a relatively poor schema for learning the optimal way to manipulate items in 3space, despite the fact that I live that space.

Learning to solve the puzzle would mean that you learned how to solve it without memorizing a technique.

There is a big difference between actually solving the cube and learning how to 'solve' it using some technique someone else came up with.

Solving it means that you analyzed the workings of the cube, figured out a way to return it to its original state without access to some outside source of information on how to do it.

Screwdrivers probably shouldn't count as a 'solution' in this sense ;)