i don't have a dog here and i've never taken any of my dogs back home to the beach, but doesn't sand make dog poo dry up easily and decompose more naturally? correct me if i'm wrong, but i personally believe having the dog poop in a secluded beach area not frequented by people and burying it properly is better than having to put it in non-biodegradable plastic for further disposal in the trash bin.

whenever we have sand available back home we cover up dog poo in our yard with sand to get rid of the smell right away and make it dry up. it will then be easier to clean it up to bury it in the soil. our garbage collectors complain and sometimes refuse to take our garbage bags if they smell dog poo in them.