The poor behavior on ships would go away if there was a slight investment in enforcement. Rules are posted, explained, etc. but when there is no enforcement then what's the point. Not to embrace debate but a few are:
-Chair Hogging
-Bathing suit attire in Lido buffet
-Non potty trained kids in pools
-Proper dinner attire
All of these have rules and guidelines but are rarely enforce (except for maybe the swim diapers in water features). Start by picking one to enforce and behavior may start falling in line.