First, eggplants and zucchini are fruits too, and both are sweet, just not banana-sweet (in fact, try zucchini bread if you haven't - best shit ever). Second, many veggies are sweet, like carrots, onions (though it's masked until cooked), and ...uh... sweet potatoes. Third, good tomatoes are absolutely sweet, not like candy but especially the little salad tomatoes aren't very far removed from a grape, which I think we agree are a fruit. Then there's olives, that bizarrely savory, dark fruit. They're delicious but I'm pretty sure they're from another planet.
So overall I think, if we're going to go by flavor, then imo acidity is the least ambiguous differentiator. Still not perfect, I'd rather just call it a fruit if it has seeds and isn't a pod. I'll give it to you on texture though
I don't think vegetable sounds right either. No one crushes up broccoli or carrots to make sauce for pizza and you don't add tomatoes to your roast veggies.
I love playing around with recipes so have indeed made broc and carrot sauces, but this is kind of all about what feels right to say. And I think that there's a lot of cases where it feels wrong to describe tomato as a vegetable. Kind of how I'd feel odd calling lettuce a vegetable.
Not sure where I said that, I was referring to nachorella's comment up thread. If you want to know my definition, it's pretty much aligned with the science definition. Fruits: the parts of the plant containing seeds (with the exception of pods). Vegetables: the rest of the plant (including pods)