i think OP might be thinking along the lines of, "how many working programmers need to know or use calculus in their day jobs?" sure, CS researchers working with physical medium like robotics or computer vision need to use calculus, but the millions of people writing code to shuffle data back-and-forth between sources (which is lots of programming jobs) don't need to know a single bit of calculus

That is exactly what I was thinking. I do not deny that there are many specific areas where Calculus is useful in programming. However most working programmers won't encounter them.

But what if they encounter them?

"I could theoretically develop a solution within a day, but I have no idea what you are talking about!"

I hope such programmers make sure that they can work on the next twitter and such things and don't have to implement solutions for financial controllers and the like.

Well, there is definitely a strong distinction between "programmer" (a trade) and "computer scientist".

I'd argue that beyond arithmetic and maybe a basic understanding of functions (e.g. f(x)), most "programmers" need to know very little math. But they also tend to produce shoddy, inefficient code and look at problems as "moving bits around".

Computer Scientists on the other hand need to have spent some time understanding the theory of computation. Calculus is one way of computing things, so is lambda calculus, and turing machines, and formal grammars, various algebras like regular languages, etc. Slinging code is just another way of computing things to a Computer Scientist.

Given this, most typical programming trade jobs are approached by Computer Scientists as a computation problem (or at least an application of a computation theory) vs. just hauling electrons about. This gets you something both qualitatively different in their code output as well as quantitatively different.