Why do so many websites do majority language redirects?

Lately I've been spending a lot of time in the French speaking part of Switzerland. In being here I've noticed an awful lot of websites, including big names like paypal and google, breaking a major usability rule- try as I might to go to British paypal I often find myself redirected to a horrible Swiss German language version (most natives in this area don't even speak German!)

I've encountered this frequently in my time elsewhere, and it does seem to be somewhat in decline. But still redirects based upon IP addresses rather than user settings persist.

My question then: What possible justification is there to do this? I think its fair to say we all agree it is bad usability. But nothing in this world is black and white. What are the advantages of breaking this rule?- I have to believe paypal is not doing it out of pure idiocy.