Just not done, Life Jackets in calm seas impede the ability to function. They are bulky compared to a Life Vest for combat. Flight deck crews wear reflective ones like crossing guards wear. Just not a typical on deck wear except in rough seas. May sound stupid to those not in Navy, but that is how the Navy operates. It’s not changed since hubby was a Sailor working the Flight Deck, and he’s been retired since the 80’s.
Here is the thing.
In industry, I am required to wear PPE that impedes function all the time. So much that it can cause a hazard.
But we do it because it might save a life.
I have often laughed at the “Safety” regs in government service. Simply put, I (as in myself) would be arrested for what passes as safety in government sectors would be done in my plant.