Programming languages are much easier to learn than natural languages. The grammars are smaller and they don't rely on learning a massive list of exceptions like certain language do (such as Dutch, my second language).
Counterexample: C++. The “exceptions” are different, but they’re still there: inconsistencies and complexities in syntax, API design, and so on. These are systems designed by humans, subject to the human understanding of language.
Learning a programming language and learning a natural language are very similar, even if the languages themselves differ greatly in their structure and purpose. The only way to get good at programming is to do a lot of it, so that the basics become second-nature. It’s the same with natural languages: you practice speaking, listening, reading, and writing, and gradually improve as you repeatedly encounter common terms and structures.
Learning any sufficiently foreign natural language (i.e. any that you can't understand simply if a speaker of it talks slowly enough) is significantly more time-consuming than for anyone who already knows one programming language to learn, say, C++ sufficiently to be productive in it.
You're comparing learning a natural language until fluency with learning a programming language entirely. These are very different things. Most people make mistakes speaking and writing their native language.
Oh, don’t get me wrong, I agree with you. Natural languages are typically larger and more involved than programming languages, so it takes longer to attain fluency. But they do exist on the same axis. A programming language can be complex enough to take as long as a natural language to learn to speak fluently and idiomatically.
