Traffic lights are totally fixable, there's just a huge amount of legacy hard and software systems. Ten years, better tracking systems, and some fuzzy logic. Problem solved.
I agree completely. There's a huge value to learning a number of other languages and they will help you approach projects from different conceptual angles, but most important is the ability to approach a project. You'll learn more about how things are really working under the hood and the limitations of your chosen language by building one substantial modular project in that time. Visual feedback is definitely hugely important too. I couldn't agree more that working on it every day is essential, if you want to get great, code isn't a job, it's life. Just like learning Japanese, if you want to really internalize what you're learning, you have to immerse yourself.