Try to write a commercial OS that can compete with IOS, Windows or Linux. I doubt it is much easier, there are so many features people expect from a modern OS.

Try to write a commercial OS that can compete with IOS, Windows or Linux. I doubt it is much easier, there are so many features people expect from a modern OS. The point is that when you compete with the best in the world in any area then it will be hard to win. Low level code is only easy when low level code isn't an important part of your product. For example backends to web apps, you don't write any low level code for them. The networking is handled via application server frameworks, the data storage is handled via pre packaged database programs so you don't even have to open a file etc. It isn't low level, it is just high level glue code between different libraries. This works just fine since you aren't trying to compete using low level code, so using off the shelf products without almost any code written by you is fine. But when your product requires you to compete using low level code then it is really hard.