Why is the EU not tough on CO2 emissions from ships?

Denmark is the home of Mærsk, the world´s largest container shipping company

The European Union has taken (too) tough measures against CO2 emissions from cars, trucks and airplanes. But why has the EU been so passive with regard to emissions from ships (with estimated 5% of global greenhouse gases, and double the carbon pollution from aviation.)?

The key person for keeping shipping out of the CO2 emissions controls is the Climate Action Commissioner from Denmark, Connie Hedegaard. That is why the New Europe Magazine
recently sent an open letter to the commissioner:

There is something rotten in the Kingdom of “Denmark,” indeed, dear Commissioner, and in this case Denmark stands for certain Commission services responsible for CLIMA and MOVE. Otherwise, how can one explain that in legislating for the CO2 emissions tax on maritime transport, the Commission assigned the issue to the International Maritime Organization, IMO, while refusing to assign the same issue in aviation to the corresponding International Civil Aviation Organization (ICAO)?

As a consequence, aviation (which counts for 1.6% of global emissions) will be taxed as of 1 January 2012 while shipping (responsible for 2.7% of total emissions), God knows when will be taxed, if ever, certainly not before 2050 (according to your Communication COM (2011) 112).

The result of this situation, dear Commissioner, is that the EU budget is losing millions every day, which it will never recover, while you fail to exert any kind of control over an industry, which systematically and heavily pollutes the EU and the world. “Intellectually speaking” dear Commissioner, someone under your nose, has granted preferential treatment to the shipping industry with several billion Euros lost to the Community and Member States budgets every year.

Hedegaard has lately been speaking about a "possible" EU level proposal in case the IMO does not come up with a solution:

In a statement on 28 June, Climate Action Commissioner Connie Hedegaard said it was "high time" for an agreement with the IMO.
"Much as we prefer a global solution, the member states and the European Parliament have asked the Commission to present a possible proposal to reduce shipping emissions for 2012 in the case the IMO fails to find a solution," she said.

Not very strong words, from this lady, who always has been demanding strong action against all kind of "polluters".

Could it be that there really is something rotten in the Kingdom of Denmark, as New Europe thinks?

Before trying to answer the question, it may be useful to know that Mrs. Hedegaard´s native country is the home of  Mærsk, the world’s largest container shipping company.