What's most annoying is that local companies make exactly the same mistakes. Digitec, Migros or Galaxus they all default to German. And I use Accept-Language as well. I understand this is a special case and the heuristic works in most cases, but when you're a Swiss company operating in Switzerland the odds are slightly different. Only 63.5% are native German speakers.

But google is by far the worst, since I'm always logged in but switches languages based on IP.