[Discuss] Wasabi - or not Wasabi?

So I was in the supermarket today and picked up a tube of wasabi. Never before do I recall looking at the ingredients but this time I did. I noticed that the "wasabi" was actually "wasabi flavoured horseradish". Then I looked more closely at the other brands and they all said the same.

So, what's the deal?? Have I been eating "wasabi flavoured horseradish" all my life in the States without tasting the real thing? Then I wikipedia'd "wasabi" and found out that the plant is rarely grown outside of Japan. What do they serve at Japanese restaurants?

Just curious.