Is a Hamburger Considered a Sandwich?

This is because of that Antarctic Panini Press, isn't it? https://news.ycombinator.com/item?id=36833252

I find it curious that a few people have used analogies to cucumbers and tomatoes. The botanical definitions of "fruit" and "vegetable" are more or less mutually exclusive. They are sort of antonyms of the produce world. But it seems that people generally agree that "hamburger" is a subset of "sandwich", an umbrella term for a lot of things. So I don't see that analogy being apt.