No, it's not a plural that just happens to lack an "s", it's an uncountable noun, which is grammatically singular regardless of how many actual pieces of fruit it describes. To count fruit and put it in plural, you use "piece" with it. Otherwise it's singular.
(This doesn't apply to different kinds of fruit though. Then you can say fruits, although kinds of fruit is probably more common.)
It's the same as "rice". We say the "rice is cooked," not "
the rice are cooked." The noun we use with rice to make it countable is grain (although obviously cup, gram, handful etc. work too).