I think the issue of €80 green fees is a non-isuue in this case. Locals are either members, or are members in Cruit of Doneagal or somewhere in the North. Locals will never pay green fees as there are so many opportunities to play these courses at cheaper "Open Day" rates or for free.
In all my years playing golf in Donegal, I never heard of anybody paying a green fees to play another Donegal (or Derry or Tyrone) course. If you're a pensioner in Donegal, you can play in seniors competition held regularly at nearly all the courses. I think it costs around €10 to play in these competitions. You can play many of them in senior, junior or intermediate scratch cups, Open Days, Open Weeks, Mid-Week competitions (for example Dunfanaghy's 14 hole competition) for a fraction of the cost.
Then we get to the inter-club competitions where you play for free (and if you're feeling cheeky, you can call around to the club and play a practice round many days beforehand). There's a Donegal Senior Scratch League, a Donegal Senior Leage and a Donegal Minor League. There are so many inter-club competitions, it's mind boggling. Then you have the Ulster GUI (Junior Cup, Pierce Purcell, Jimmy Bruen, etc.) competitions where, if you're drawn against a biggie like Royal County Down, you also play for free!! When it comes to inter-club competitions, Ireland is just crazy. In winter you also have the North West Alliance where you can play all the 18 holes courses for a small amount. So, locals do not pay green fees, not even the the GUI rate.