Agree, same in programming, you could see that f = (a,b) => a ^ (10+ b) , but not understand what it actually means and why 10 is there and not 9.

Another example is the use of commonly known constants, such as pi, i or e. No paper will define those constants and explain indepth what they mean, so you need prior knowledge or to find external resources. I think for such complex papers you will find many such cases where extensive prior knowledge is needed.