The ancillaries display debate may be raging in the U.S., but in Europe the rules are established.
Unlike in the U.S., the global distribution systems in Europe are regulated and there are rules about the display of airfares.
These rules are purely applicable to GDSs and do not apply to an online travel agency or an airline.
Below are some of the the relevant sections of the rules and here [pdf] is a full copy.
REGULATION (EC) No 1008/2008 OF THE EUROPEAN PARLIAMENT AND OF THE COUNCIL of 24 September 2008 on common rules for the operation of air services in the Community ...
(16) Customers should be able to compare effectively the prices for air services of different airlines. Therefore the final price to be paid by the customer for air services originating in the Community should at all times be indicated, inclusive of all taxes, charges and fees. Community air carriers are also encouraged to indicate the final price for their air services from third countries to the Community.
Information and non-discrimination
1. Air fares and air rates available to the general public shall include the applicable conditions when offered or published in any form, including on the Internet, for air services from an airport located in the territory of a Member State to which the Treaty applies. The final price to be paid shall at all times be indicated and shall include the applicable air fare or air rate as well as all applicable taxes, and charges, surcharges and fees which are unavoidable and foreseeable at the time of publication.
In addition to the indication of the final price, at least the following shall be specified:
(a) air fare or air rate;
(c) airport charges; and
(d) other charges, surcharges or fees, such as those related to security or fuel; where the items listed under (b), (c) and (d) have been added to the air fare or air rate. Optional price supplements shall be communicated in a clear, transparent and unambiguous way at the start of any booking process and their acceptance by the customer shall be on an ‘opt-in’ basis.