Raw Data - I'd be the first to agree with you that it's a major struggle to start an airline unless you/your backers/your family has very, very deep pockets.
I don't agree, though, that passenger's needs are met with the current transatlantic market mix. I have the CAA stats which clearly show that there's very viable demand on a number of North American routes - and that's not taking into consideration other viable routes to Africa, the Middle and Far East and Australasia.
Lauda Air - amongst others including Emirates and Singapore Airlines - has clearly demonstrated that the size of your home territory does not determine your passenger loads or profile. If you've got a quality product with low fares and can create a decent hub (or tie in with a feeder airline) then you'll have people coming from all over to fly with you.
And don't forget the 'low fare' effect - Freddie Laker's 'Forgotten Man'. Remember, back in 1975, the CAA's argument - as put forward by BA, BCal, Pan Am, TWA et al was that the transatlantic market was very adequately served, thank you, and that any new entrants would just spoil things for everyone. Freddie's premise was that if you offered fares that were low enough (£54 one way in his case) you'd stimulate the market tremendously. And so it proved when Skytrain launched in 1977.
As far as the Scottish market is concerned, I believe that there is a significant, untapped market for whom transatlantic and other long haul travel is just too much of a hassle. Who in their right mind wants to leave their home only to fly over it several hours later?
On the political side, I agree. I think that this is simply a case of Helen Liddell playing lip-service to the rising tide of public opinion (in large part generated by the Sunday Times' Fare's Fair campaign) that there should be more Scottish transatlantic services. Certainly, neither the Scottish Executive nor the Scottish Office have offered to put their hands in their sporrans for the establishment and/or marketing of such services! However, to develop Scottish tourism - and thus stimulate demand - Scotland needs direct air services. There are very few European countries that I can think of where all their visitors need to transit a third country in order to get there!