I like to think of it as the distinction between editor and reader. Like you said, it's quite easy to read code. I heavily agree with this. I don't professionally write C but I can read and kinda infer what C devs are doing.

But if I were an "editor," I actually take the time to understand codepaths, tweak the code to see what could be better, actually try different refactoring approaches while editing. Literally seeing how this can be rewritten or reworked to be better, that takes considerable effort but it's not the same as reading.

We need a better word for this than editor and reading, like something with a dev classification too it.