Um, i'm sorry but I think you've completely missed the point I was making. Shy people don't intend to make people 'work ridiculously hard' to get to know them. Sometimes its just hard for them to be open, especially when they think you're thinking such things.
Me personally, I am shy because I don't trust anyone too easily. Nearly everyone I have got close to has either died or completely taken advantage of me. I do eventually open up to people, but it takes me a while.