Which is exactly why it is correct. The only time peoples' would be acceptable is in the case of talking about specific groups. The British and German peoples' language are not the same.
people's = of (the) people
peoples' = of peoples
It's confusing, and there are different camps of thought. As was said earlier, I don't see it as a big deal. Everyone knows the intent, which is to simply show possession. I use the word "irregardless" all the time. It's not (truly) a word, but who cares? *shrug*
Jeremy

