If naH means fruits or vegetables, how would you specify that something is a fruit?
Just like most English speakers who are not specifically biologists wouldn't specify that a particular fruit is a pome.
They're either be less specific and say "fruit" or be more specific and say "pear" or "quince" or whatever.
Anything in between is technical jargon reserved for scientists.
Or to put it differently: how would you complete this sentence? "Pears and apples are both ....".
You'd probably say "fruit" rather than "pomes".
Similarly, Klingons would say that naHmey bIH na'ranmey peb'otmey je.
(And for that matter, is a cucumber a fruit or a vegetable? It has seeds, so it's botanically a fruit, but I don't think anyone would put it into a fruit sald. Just all 'em all naHmey!)