Yes - any advertised price (media, billboards, website) should include all 'non-optional' taxes, fees, charges and in addition the highest credit/debit card fee that would be applicable to a round-trip journey.
For example on Cryanair's home page they show a 'cheap-flight' from Bristol to Dusseldorf of £12.00 (and note that fares don't include optional Fees/Charges).
If I had (or could get, which I can't) a Prepaid Master Card then I could buy this for £12 but the vast majority of consumers don't have such a card. They would pay an extra £4 per flight, per passenger.
So what I am saying is that in addition to non-optional TFCs the price should include the airlines credit/debit card fees. If the airline has more than one fee then the highest of all of these fees would be included.
So Cryanair would have to add £4 to all of their displayed airfares, but you could get it for less if you had the right card.