Patrick,
Many Scottish and Irish courses have narrow fairways, but not all of them have all fairways narrow or are narrow everywhere from tee to green. Muirfield like I said was pretty narrow. Prestwick also has some very narrow fairways, some less than 20 yards wide in the most desireable (i.e., level) landing areas. But you can look at Troon, North Berwick, the New, Jubilee, Ballybunion, Lahinch, and on and on and you can find some awfully narrow fairways on some portion of the holes. Like I said earlier it is not uncommon for fairways to narrow to less than 10 yards in places, but you might also find some places where they widen to 50+ yards, on the same hole.
Plus there are different types of 'narrow'. Some courses have gorse right up to the very edge of the fairway. If a fairway is 40 yards wide with gorse on both sides that's much narrower in reality than a fairway that's 20 yards wide with the foot deep wispy rough you'd find at say Prestwick or Troon.
I remember one hole at Dornoch (I think it was 7, this was 15 years ago so I can't remember for sure) that played uphill, into a stiff breeze, with a narrow fairway that had acres of gorse on both sides. I didn't think I'd see a scarier tee shot in Scotland. Until I played a few rounds on Troon's munis, they were ALL like that, I lost so many balls there I started using ones I found looking for the ones I'd lost rather than wasting any more new ones since I still had a few rounds on big name courses left and knew I'd otherwise run out of balls!