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…