people pay at least a hundred thousand extra here for waterfront property, and expect that they own the beach to the high tide mark. That part is easy.
But, which high tide mark, since there are several? And beaches build up or erode, so the high tide mark often moves up and down. And if you lose beach, who pays to put some sand back? What if you lose beach because of the jetty put up to save someone else's beach?
Some of this goes back to British land grants, and others to the constant battles over riparian rights, but at least it's just some asshole homeowners putting barriers on "their" beaches to keep people out, not fights over cities vs. farmers for water.
My attitude is that nobody should own waterfront property, with few exceptions where it makes sense (like marine businesses). The view is nice, and you can walk past your front yard and fish or clam and tie up your boat, but where is it stated you have a basic right to do that? Tough shit-- wild beaches and riverfronts are fast disappearing and preserving them is more important than a the convenience of owning them.