Experienced, smart, and savvy programmers will make all sorts of mistakes in their code, even stupid mistakes. It takes an immense amount of effort and savvy to reduce, mitigate, and recover from bugs in production code. Meanwhile, management applies pressure to ship new features. The kinds of teams and people that manage to ship high-quality code on a regular basis are teams with a lot of different types of people on them—you need someone who can make the case to management that these efforts need resources and are in the best interests of the company, you need someone to drive team culture and figure out what kind of practices will reduce bugs, you need people who work on automated tooling, you need people to run disaster scenarios, you need technical coders who can make frameworks that are easy to use but hard to misuse.
Nobody I met came with any of those skills out of college.
Multiply the difficulty when you’re working with distributed systems, like this one.