I could be wrong on this, but from what I've been told the laws are the same - it's the ports that are different. In other words, the ports in Florida have constant prevailing winds that keep the ports cleaner. Baltimore is unique in that the port is on the Chesapeake Bay and much more inland.
(In fact, it takes 8 hours to transit the Bay one-way from Baltimore to the Atlantic Ocean because of the length and the speed limit. It actually takes longer to go from Baltimore to Bermuda than it does to go from New York to Bermuda even though New York is further away.)
But because the Port of Baltimore is inland, they don't get the prevailing winds and it's more susceptible to smog. Plus, the Chesapeake Bay has other EPA laws and regulations because of the unique situation it has, which is very fragile. There really aren't any ports in the U.S. quite like it, so it's hard to compare it against all the other ports.
One great feature about sailing out of the Mid-Atlantic/New York/Boston areas is that they are closer to Canada/New England ports, so they do offer something those sailing out of Florida don't offer.
As for sailing to the same ports as those out of Florida, when you look at where ships can go, there aren't a whole lot of options no matter where they sail out of. And when you look at how far they can go in a week, they are very limited.
The whole thing is driven by supply and demand. And out of this area there's a pretty good demand because alot of people don't want to fly. It can cost more to fly to Florida out of this area than it costs to fly to California - go figure that one! When you look at the population within a 3-hour driving distance of Baltimore, that's a pretty huge amount of prospective cruisers.
I don't read too many comments because most of them are written by people with uneducated opinions who have no idea what they're talking about.
But one thing is for sure, it really sucks that Norfolk spent alot of money to build the new cruise terminal and revamp the area in hopes of bringing ships there on a regular basis. Norfolk got a big commitment from Carnival Corp. and took them at their word, so they invested alot in the infrastructure to provide Carnival a nice terminal. Now, Carnival is defaulting on their promises by saying, "If we have to play by your rules, we're going to take our marbles and go home."
As with most things in today's world, it's more about the politics than doing what's right.
If you notice, other cruise lines aren't having these same problems.