Why would FR operate from THREE North-West airports to DUB multi-daily? Why would Euromanx fly to MAN and LPL from IOM? Oh yeh...demand.
Just because they operate a route 30 miles down the road, what about the people that live East of Manchester? You can't just think about people in the MAN and LPL areas.
MAN and LPL could both easily support many routes by the same airline.