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).
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.