Near park resorts generally enforce the restriction of needing some kind of reservation at the resort to park there, and even then parking is limited to three hours. The obvious reason for that is to prevent guests from just using the parking lot to provide easy access to a park (which large numbers would do if parking were allowed, thus making it impossible for guests staying at the resort from being able to find parking). The exception to that is when you already have valet parking for the day at the resort at which you are staying, which allows you to valet park at any other resort that has valet parking and not pay anything additional.