So there is

1. 100% plant based food, labeled for example “vegan sausage”
2. 100% plant based food, labeled for example “sausage”
3. X% meat based food, labeled for example “meat reduced sausage” or “sausage with added vegetables”
4. X% meat based food, labeled for example “sausage”
5. 100% meat based food, labeled for example “sausage”

Personally, buying 2 or 4 I’d be surprised that these products contain plants. But I fail to see how 1 and 3 would surprise anyone anymore. “Vegan” and “vegetarian” are terms I’d expect any adult to understand as “does not contain meat/anything from an animal”. So, calling anything “vegan sausage” clearly communicates that it is “vegan food in sausage shape” or “vegan food that is intended to replace sausage”.

No one in their right mind would think of olive oil as something to lubricate some olives…

Correct me if I’m wrong but isn’t this 80% meat and 20% vegetables and thus not vegetarian? If so, this isn’t the same kind of product as an actual vegetarian/vegan patty that is made from vegetable protein only.

I agree with you that the product you linked is labelled confusingly. But it won’t ever be called “vegetarian patty” but rather “meat reduced patty”.

Edit: You get confused not by vegan burgers (no meat contained) but by non-vegan burgers (less meat contained) and thus by the meat industry, right?