Milk is definitely sweet. But I didn't notice until recently, maybe a year or two ago! I rarely have milk because there's no fridge in my van, so when I did put some in my cacao after quite a long abstinence I noticed a real difference in sweetness, didn't feel the need to put in any additional honey. I was kind of mind blown too 😄
For tomatoes it depends on the kind I would say. Those little cherry tomatoes can be super sweet! But the big ones are quite sour, that's true.
It's kind of fun to think about how to explain a taste ^^