I just did a bus-travel enquiry from Barrow to Workington and it gave me a 4-hour itinerary changing at Ulverston, Windermere and Keswick (there are currently no through trains). So there is work to be done!
Though there is the issue that (in general) Cumbria is quite a divided county in terms of where people identify and associate with. Most of the towns in Westmorland, particularly the south (places like Kendal, Kirkby Lonsdale, etc) generally gravitate towards Lancaster for their services. Barrow is in a similar position (though because it's larger and more isolated, is perhaps a bit more self contained). On the other hand Cumberland and the Eden Valley tend to look to Carlisle as their main centre. You notice this on the train services along the coast - demand is stronger between Carlisle and West Cumbria and then picks up again once you get to Millom, but is relatively minimal between the two (some commuting between Millom and Sellafield excepted).
Interestingly, before the councils were reorganised to have Cumberland and Westmorland/Furness, there were actually proposals which would have put the Eden Valley in with Cumberland and then combined the south lakes (including Kendal), Furness, and Lancaster/Morecambe. This would have perhaps solved some issues around the boundaries - as it stands the 555 would cross the boundary of the franchise and I believe is worked both from Kendal and a Lancaster/Morecambe depot.
I suppose this is no worse than many other rural counties - in many cases (say, Wiltshire) you have different parts of the county looking to different centres, some of which are internal and others external. But it is more of an issue for these franchising proposals than metropolitan ones which generally have a clearer centre.