Don’t be confused, I bet they just came across some mess of duplicate content as can easily happen on international websites.

So for example I guess if you have only one domain hosting US, UK and Australian content that’s pretty much identical, you can get around it by geo-targeting the sub-folders appropriately.

Source: http://www.seomoz.org/blog/new-info-from-google-and-yahoo-tilts-the-geotargeting-balance

By using the canonical tag you ensuring that one version of a particular language content will never rank, in any engines.

The point of being a business that operates in more than one country is that you have a website that has content that can be shown to users in all of those countries. The canonical tag can solve duplicate content issues, but should be used to canonicalise two pages aimed at different markets, in my opinion.

If I operated in the UK and US (for instance), and used the canonical tag to point all the US pages to their UK equivalents, people searching in the US would never see the US pages, and the UK pages would never rank very well in the US SERPs.

But if you have 10k pages it’s going to be difficult to scale the process of making them all unique. I think the rel canon can be a good hack or work-round, do you not think it could work in that kind of situation?