You mean, "Why don't they use a language you understand, instead of one you don't?"... Why expect they should? I don't think math notations can be interpreted

You mean, "Why don't they use a language you understand, instead of one you don't?"... Why expect they should? I don't think math notations can be interpreted in different ways usually is right. That would defeat the purpose of using them, if the meaning wasn't exactly clear. And maths notation is more compact, a lot more. Even assuming a translation between the 2 always is possible or makes sense.