The plural -s ending forming a noun out of an adjective is a fun little corner case in English morphology. "Politics" is explicitly patterned after Aristotle's τά πολῑτῐκᾱ́, "affairs of the state." "Mathematics" is from Latin mathematica, which is singular. "Physics" is attested as "physic" in older English, which conforms with its singular declension in Greek φυσική. I'm assuming this affix develops out of the truncation of a noun phrase, or the use of adjectives as substantives? Like, "Which candy do you like? I like red ones, I like the reds," type constructions. But it's fun that in the development of the -ics ending there's an English construction that's used in a way frequently parallel to the Greek derived -ology, or the older Germanic -craft. Seems especially suitable for big, complex fields like mathematics that have lots of subfields. Like, there's more than one mathematic! That makes a lot of sense to me. Though I guess American verbal agreement patterns still prefer a singular verb here, in contrast to the Commonwealth usage.
Note on this "math" versus "maths"; the number is consistent even with abbreviation.
(Brits make fun of Americans for saying "math", since the word obviously has an 's' on it; for years I've responded that in America we only have one mathematic.)
But this does make me ask the very silly question of whether British students ever take an econs class.