Mark, there are a lot of things I don't like about golf in the U.S. (carts, overwatering, etc.), but I think you go too far in your criticism of Americans playing in the UK and Ireland. I don't have any time for people who play courses just to brag that they've played them. To me, that's a trophy hunter. But not everyone who plays 7 courses in 7 days is a trophy hunter.
Like most Americans, I have 2-3 weeks of vacation a year. Absent extraordinary circumstances, I won't spend a month abroad. If I go to the UK or Ireland with my family, I'll likely play a couple of courses squeezed in along with sightseeing. If I go on a guys trip, I'm going to damned well play as many courses as I can. When I return to Ireland, I'll play Lahinch. When I go to Northern Ireland, I'll play Portush and Newcastle. When I go to Scotland, I'll play Dornoch. Am I trophy-hunting? I don't think so--I want to play the courses that appeal to me the most and some of the famous courses fall into that category. Some lesser known courses will as well.
And, I'll walk (obviously), most probably without a caddie.