The clearest example of this in the UK is Stansted. Built for political reasons by a Government-owned monopoly, it was built in a random location chosen only because it was the site of a wartime airlield. It's recent commercial "success" was due to cross-subsidy alone, and airlines have either moved to better-located airports, or are stuck at Stansted due to insufficient capacity elsewhere.
It's a good job the UK Government didn't build offshore in the 70s!!