BBQ culture is different in different parts of the world - I experienced what you describe in Switzerland once (bring and grill your own food). Where I’m from, it’s bring your own booze but host is expected to provide all the food. Where my partner is from, you’re expected to bring either dessert or salad - but not booze or stuff for the grill. I think you’re reading too much into some fairly minor difference in etiquette. If you want to experience real culture-shock, try using a sauna in a German-speaking country…

Oh, it's not a "culture shock" kind of thing. I actually had no issue whatsoever going to a Sauna or even going swimming on the FKK hours. Like I said, I studied in a German school so I kinda knew these things are just a natural part of German life.

And it's not like I was "bothered" by him bringing his own food or wanting to cook it. It just seemed the guy was completely missing the point by being too focused on the "meal".

I just want to give one example of what I meant by "cultural differences", not that this one story cemented my opinion of Germans. Somewhat like trying to explain to an Italian that the North American idea of "getting coffee" means grabbing a Starbucks and walk around - or worse, driving to get it on a drive-through.