Sven,
I guess that I consider myself lucky by your definition. In three trips to Ireland and three to Scotland/England, I have had only two caddies who earned their primary living at some point from caddying. As mentioned above, one was Graham Matthew who caddied for twenty years on the LPGA (and is a member of NB).The other was at Swinley Forest who caddied on the LPGA and the European Tour. Every other caddie either was a member or a kid earning a buck.
My estimate is that the median tenure as Members at the clubs is 30 years.
I am excluding Castle Stuart and Kingsbarns which really are US resorts transplanted to Scotland. The caddies at both were good, but the scripts were American. At American resorts, my experience is more mixed. Brett and you at Bandon were great. We had an excellent caddie for two rounds at PH2, and one where I ended up carrying my own clubs at PH4. The caddies at MP/PN/SP were good but not great. Our caddie at Pasatiempo was terrific.
Ira