Fruit (ripe fruit) tastes delicious because it needs to be eaten by animals, and then the seeds can walk around with the animal's feces, which helps plants reproduce, which can also be explained by Darwin's theory of evolution. With such a sour taste as lemon, no animal will like to eat it, which is likely to lead to the extinction of this plant. Therefore, the evolution of nature is unlikely to have such a thing as lemons.
Some fruits also taste sour when they are immature, because at this time their seeds are not yet ripe and they do not want to be eaten by animals at this time.
However, it is true that some fruits still have a sour taste when ripe, but fruits like lemons, which are very sour from beginning to end, are not common.
