Agreed. Public beach is public beach.
There is an gov't office (assuming it still exists) that determines public beach access thru private land when someone is developing up against a 60 mtr setback. They look at everything and decide if a public access path is needed or not. It probably depends on current public use of that particular beach, proximity of other public beaches, other access points, etc. But then over passage of time, things get ignored, nobody challenges them, and a resort/hotel/condo will leave the path unmaintained and start denying access on the beach itself.
I'm guessing that doesn't happen at Sosua Beach. It's too popular of a beach. Although I do see public usage changing dramatically. Sundays ain't going to be what it used to be.