The ability of the infant brain to pick up as many languages as surround it is a testament to its incredible plasticity, not an indicator that it's "easy". If

The ability of the infant brain to pick up as many languages as surround it is a testament to its incredible plasticity, not an indicator that it's "easy". If you doubt that, good luck becoming even halfway productive[0] with a second natural language as an adult in anything close to the amount of time it takes to become productive with a second programming language. 0. Productive, while a fairly weird word choice, can here be taken to mean "able to consistently engage in and with non-trivial communication" the way that productive in a programming language can be taken to mean the same for non-trivial features and tasks.