Yeah, yet another stupidly unenforceable law. If you see the cops milling around at the beach are you gonna come in from the surf? Nope, you're gonna swim away down the beach....
I realise that it saves money, which is a good reason in some circumstances, but not when it impinges so heavily on personal freedom and individual responsibility. The risk of dying should be enough to make people wear a life jacket if they feel they are not confident swimmers.