[bananicorn]

Let's take the sausage for example.

If you have a clump of meat, it's not a sausage. If it's brought into shape by some kind of "skin", (which nowadays often is artificial "intestine"), then it's a sausage.

So, I'd argue that the word sausage for example describes the form factor, more than the actual content.

I don't think the case is much different in the case of a burger - if it's clearly declared as a veggie burger, one better assume that there's no meat in it.

The distinction between meat and veggie burger is probably even less difficult than the distinction between a veal and a pork burger. You wouldn't want to have to use different names for meat products if they were made from a Kangaroo, or Ostrich, would you?