> I still find it hard to comprehend how a one of the tools of a taxi calling app has this much complexity and have thousands of engineers working on it
You can really say this about almost anything once it's established. A startup can seemingly get really far with just a handful of people, but that startup is undoubtedly also dealing with only a handful of the use cases and edge cases. They also don't have legacy to maintain and upgrade. They also don't have all of the issues of scale.
Couple that with the fact that as outsiders we likely only see a tiny fraction of what the system ultimately needs to deal with.
You can really say this about almost anything once it's established. A startup can seemingly get really far with just a handful of people, but that startup is undoubtedly also dealing with only a handful of the use cases and edge cases. They also don't have legacy to maintain and upgrade. They also don't have all of the issues of scale.
Couple that with the fact that as outsiders we likely only see a tiny fraction of what the system ultimately needs to deal with.
I'd get this sort of feedback here whenever talking about Khan Academy's work, so I ended up blogging about it to give a sense of how much more there is than what people think about: https://www.kevindangoor.com/posts/why-khan-academy-has-so-m...