Why functions are not case-sensitive?

Question

I think (what I understood is) program makers don't think it necessary. In the case of variable, we are able store more value with more variable by changing case-sensitivity. It helps us to make many variables as we want by making simple changes in variable names. On the other hand, function don't need to store anything. It just functions when parameters are matched to complete the function. So, there is no need to use Case-Sensitivity to make it different. But for your understanding the code purpose, you should practice it to help other programmers understand your code.
Hope, you understood. If I'm wrong, please give me clear explanation.
Thank you. :)

Answer 1

Even if variables are case-sensitive, You should avoid naming variables with same names, but with different cases.