FR@STN and Hotel Tango
If we look at your posts you have highlighted the difference between the UK and elsewhere in Europe and the US.
In the latter low cost operators are often located in separate terminals or wings of terminals In the US you will find Delta, United and American segmented from Southwest, Spirit and Frontier- there are operators who can fit into either model e.g. JetBlue.
In Europe the division may be low cost via the others (Schipol, CDG) and in some places has resulted in low cost vs former national carrier (Barcelona with Vueling and legacy one side and EZY, FR etc on the other).
In the UK we have really abandoned the legacy model for short haul which is why some UK pax will travel with airlines like Swiss which haven't. UK pax have embraced the low cost model more extensively than elsewhere. Whether this also happens to long haul remains to be seen but Norwegian Thomas Cook and Jet2 are starting to invade that space too.
BHX has insufficient long haul traffic to warrant separation and much of its Long Haul product is low cost (of provision if not service eg. Emirates) anyway. Legacy business oriented long haul is really only Heathrow and to a small extent Manchester.
FR you are correct for the UK and Hotel Tango has valid points for Europe