I have to disagree with a number of things that you say. First many Americans do eat a lot of Garlic, remember there are many Italian Americans here as well as many others who eat foods from all over the world.
As far a garlic being harmful, I don't know if it is harmful if ingested but it may very well be...but I know Beck was right that it will kill you if it gets derectly into your blood stream. I have noticed that I feel a lot more alert when I'm off garlic but that may be just me.