It may be considered an “international company” but the operations more particularly their franchise are obtained locally by another local domestic corporation. That's why you will only see Burger King in Germany that accepts Bitcoin and no other countries have it,
It's true that local franchises matter, but not that there aren't Burger Kings in other countries using the takeaway site to accept Bitcoin. I looked it up myself just now, and The Netherlands and Belgium both are signed up.
I'm sure that if I check in other countries to see if there are local Burger King franchises signed up to takeaway, I'll be able to find them. It takes some time to search based on postal addresses to find them, but it works.
I find it funny how there are still articles being written about Burger King Germany accepting Bitcoin, and that while Dominos, New York Pizza, etc have all been there for a couple of years now. Just shows how little research news outlets do.