It's good to see some people from south of the US border chiming in here. I don't think there's too many people from there on this board so it's nice to get their perspective on things.
Cristinanrock, you make a good point about how infrequent Metallica plays there and that could deffinately be why they may play some more older stuff instead. They tour the US every 4 or 5 years now so we do get them a little more then you guys do. They do play those special sets in Europe as well and they spend as much time touring there, if not more, as they do here. I guess we'll never really know the answer as to why unless there's an interview somewhere or someone actually has the chance to meet them and ask exactly why that is.
Don't worry about your English at all. It's actually better than some people who are from here