I actually may be unreasonable as I have no idea about what the rest of the world do, BUT…
… I was watching an episode of Food Theory on YouTube and he mentioned repeatedly, ‘Cadbury’. I found it so weird and jarring because it is known as ‘Cadbury’s’ to me. I suppose on reflection it makes sense because I think we are sold ‘Cadbury’s chocolate’ rather than just a product from Cadbury, but it sticks and I refer to it in that sense all the time (I don’t say Nestle’s or Mars’ for example).
And it’s not just that - I go to Tesco’s, not Tesco. And whilst I don’t say it myself I’ve heard friends shopping at ‘Lidl’s’ and even Asda’s.
So is it a British thing or is pluralising companies in common usage a thing done world over?