You have the answers as to why.
I can share with you that most of the public beach accesses in Walton County do not have parking. There are "Regional Access" which have paved parking and restrooms, and there are a few public accesses which have two or three parking places, but for the most part, the county seemingly has no plan to address parking or shuttle services to get people who reside off the beach to the beach. Sure, they have added some parking here and there, and are currently working on some parking north of 30A in Seagrove. However, in the high season, you will see cars parked street side close to many of the accesses. Lack of money to purchase property is likely a concern, and at one time, the county talked about leasing some property for parking. If it is a problem now, just wait until the existing lots in South Walton are built out. The problem will only multiply as we go forward in time.