I think there is a middle ground between being completely ignorant of what one is consuming, and being a vegan/vegetarian. When I started college I started a vegetarian diet (eating very healthy, actually part of a co-op), still ended up becoming severely iron-deficient anemic. the doctor told me a) to never donate blood, and b) include red meat in my diet. I even went to a nutritionist who confirmed I consumed enough iron in my (vegetarian) diet, but apparently some people cannot absorb the iron well from non-animal sources. So in addition to taking iron pills 3x a day for a number of months, have since then always included red meat in my diet. Does it mean I need to eat it every day, or for every meal? No. What I'm trying to say, going to Americans who eat a very processed diet with lots of red meat and other meat, and chiding them that they are not vegan, is not going to go over well. It doesn't help the conversation. And there may be medical reasons some are not vegan/vegetarian.
What does help, is in general people becoming more aware of where their food comes from, preparing more of their food from scratch, and including more meatless meals in their diet. Some of the things that have gone over well in our house is vegetable soups, some traditional Greek (vegetarian-look for lenten) dishes, Mexican and Indian dishes. People LOVE food. It is more of a benefit to expose people to food that tastes delicious without relying on meat, than to give people guilt trips.
