In the past, parking was free. Then it became crowded, partially because so many people were parking there and going to the parks (and some were writing about it online and in trip reports, thus spreading the word. Not smart!) . Now, everyone who parks there has to pay, but it mainly punishes the resort guest who has a vehicle with them.
Daily Dolphin parking in October (and I believe Swan is the same), was $9.00 plus tax, bringing the total to either $9.57 or $9.59 per 'day'. We stayed there 3 days/2 nights (Fri-Sun), and were charged for 2 'days' of parking.