It's not that hard to develop lessons that meet the standards. It is time consuming and typically not paid for, teachers are expected to do it on their own time.

My state adopted new social studies standards last year and will require that they be taught in all grade levels as of next year. They allowed time for phasing them in due in part to the knowledge that there is no money behind redoing the lessons that teachers will need to develop and also no money for curriculum purchases to support it. Last weekend my wife went to a training on the new standard which we paid for out of our own pocket as one example.