I think you could replace "isn't easy" with "isn't familiar". Haskell is very likely to be the first language a developer encounters which is lazy by default instead of strict by default (for many good reasons).

So no, it's not easy in a similar fashion that pointers or double pointers in C/C++ are not easy. Or understanding call by value vs. call by reference semantics are not easy. The list goes on. It's probably the largest barrier to learning the language.

But once you get a handle on the evaluation model it becomes a lot more natural. At least that was my experience, maybe it is not typical.