Might be better off just instituting pollution taxes and not letting ships fly whatever flags they want or burn whatever oil they want. Then if cruises can clean up, good for them.
I can't read the article btw
I can't read the article btw
There are other things that aren't really great for us, but we (well, some of us) derive pleasure from them, or some of us do. Like alcohol, tobacco, cannabis, eating beef, and so on.
The best thing to do with those is not outlaw them, but tax them.
Also in many cases a particular city, say Barcelona or Venice, may want to regulate, but pollution laws are typically at the regional or national level.