You're correct. Funny enough, this is also obscure knowledge even in e.g Spanish. We use the word salario (from latin salarium) which has the same meaning as in latin: words ending in -ario (lat: -arium) is used to denote association, like in templario (templar) or revolucionario (revolutionary). For some reason, however, nobody thinks of "salario" as something associated with salt (sal). I guess it's so strange in today's world that money would be used for the specific purpose of buying salt, that it simply doesn't click.