I would agree with Jimmie. If they don't come, don't pay them. I do make exceptions to this rule if I cancel and it's going to be extended (2-3) days rather than one day.
When we are not seeing patients, they are supposed to do other things, such as calling people for annual check ups, checking on billing and putting vaccines in the state database. So if they don't show up no pay. If I cancel for an extended period, I may split the difference since all my staff is living on a thread.