The confusion stems from the way "fruit" is used both as a countable and an uncountable noun. I think English uses the plural when enumerating different kinds of "fruits" (apples, peaches, bananas), and tends to use the uncountable "fruit" for anything else, no matter the quantity.
countable: fruit, with the plural fruits
uncountable: fruit, no matter how many
In Romanian, most of the time we say "fruct" if it's only one, and "fructe" if there are more than one (two, three, one thousand, etc.), no matter if they are of the same kind or not. "We eat fruit." translates to "Noi mâncăm fructe." We say "suc de fructe", not "suc de fruct"; "suc de mere" (plural), not "suc de măr" (singular). In English, these would be "fruit juice" and "apple juice", not "fruits juice" and "apples juice". Usually, the juice is made of more than one piece of fruit - at least in Romania.
However, just like with any other thing or being, in general statements we can (although we don't have to) use the singular while meaning the plural, all of the kind. For example, "Fructul este darul naturii." (The fruit is the gift of nature.) means all of them. Not sure if in English this would not be "The fruits are the gift of nature." or if both versions would be fine too.