My doors are locked and I have a security system which is not activated during the day but does have a chime for all doors and bedroom windows. If a parent were to drop by unexpectantly they should reasonably expect a door to be answered from immediately to 3 minute time lapse depending where we are in the house and wether I am changing a diaper. I think an open door policy is ridiculous. If you are worried about your provider being up to something then they should not be caring for your child. Trust your gut. Part of caring for your child is to protect them and keep them in a secure and safe environment - an unlocked door does not provide that and is negligent. Emergency responders can get in my house using excess force if I am not able to let them in.