To go back to a subject long past (because I like this kind of shit!): “mathematics”. The plural morpheme is there because it's made up of several distinct fields of study (algebra, geometry and arithmetic being the most obvious). However, those fields are considered to make up, collectively, a whole, generally dealing with the field of numbers, so that whole is treated in English as an uncountable — or mass — noun, and logically takes the third-person singular as a following verb form.
It's just different ways of looking at it. By the way, in my “other” language, we say « les mathématiques », and that noun phrase therefore governs the following verb form, as in « les mathématiques sont très complexes ». And of course the adjective has to agree. However, in the distant past French did have « la mathématique », so it gradually evolved.
Anybody looking for pure logic in natural languages is going to find themself on a wild goose chase, by and large. They just don't work like that, or only very imperfectly.
Now, Trumps and his politic. Where were we… ? (By the way, why do we say “Rodders?”)