As a fun aside, in my family in Romania we do put lychees in a fruit salad, when we find some (usually canned).

There are two separate points here: my point was specifically that culinary and botanical categories for the word fruit do not overlap - there are botanical fruit that few people around here would consume as culinary fruit, such as olives and cumin. There may be culinary fruit that are not botanically fruit (for example, some may consider rhubarb stalk 'fruit').

Even if you are right that when asked what olives are people would say 'fruit' (I believe you'd get a variety of responses, with some calling them legumes or even spices), that still doesn't mean that people think of them as fruit. If you ask someone to pick up some fruit from the market, they won't come back with olives.

Your point is also correct, in that the culinary fruit category is culturally specific, and different cultures may regard different foods as 'fruit'. I doubt there is any culture where culinary fruit is perfectly matched with botanical fruit.