Well, sometimes they are restrictive with letting user change settings at all, including browser settings. But most of the time I don't think people know how to actually do that, and especially they dont know that this will have any effect on the site. You have to let them know in that case, but most people can see a flag on a page and they know that it stands for a language. I like the localization, its great by default but, in my opinion, you chould be able to choose language from the site to. Your point about the content is good though...
Cheers,
Christian