That is correct. To go to any restaurant that is in a Park you must have a ticket to enter the park. To go to a Resort (hotel) you do not need a ticket.
If you are staying off-property and do not have an AP, you will have to pay a parking fee when you enter the Magic Kingdom Toll Plaza. The Contemporary, Grand Floridian, Polynesian and Wilderness Lodge are inside this area. If you are going for Dinner only bring your parking receipt into the restuarant with you and they will more than likely refund you the parking fee.