I'm guessing EU members grant aviation cabotage to one another, but even if true it's probably a pretty recent thing. Throw in a penchant for dirigisme, especially on the continent, and you pretty much have your answer.
For the continental Europeans and the Brits left on the board, I have a question about your airlines. In the US we have a number of "legacy" airlines left that fly both internationally and domestically. For flights I have taken overseas, I've seen a number of our carriers like Delta, US Airways (before the merger), United, etc. present at overseas airports.
However, when I see international flights in the United States, all I ever typically see are the individual country's flag carriers like KLM, Lufthansa, BA, Air France, etc. Do you have other "domestic" carriers that you can fly internationally or do the other EU country flag-carriers constitute enough competition such that each country has one international airline option.
I understand that there are numerous domestic low-cost carriers available for your domestic flights, but it seems strange that each country only tends to have one brand present here in the United States for international lines when we typically have multiple carriers present overseas. Thanks in advance.