I’ve spent a decade in the public sector where you’ll find a little of both. In my experience the dedicated software departments produce better quality software over time. This isn’t to say you can’t do it with integrated teams spread out over your organisation, it’s just that it comes with more of a risk of two separate teams working “against” each other (usually not on purpose) when you have less “control” over your digitalisation organisation. Now, I’m actually a huge fan of doing the spread out stuff, but not for critical software. The best comparison I have from my work is medical software that has life and death impact. I absolutely think your hospital should have dedicated digitalisation teams spread out over all it’s organisations to better spot and build things that benefit the organisation, but the people writing the surgery automation software need to be in the department that does that sort of thing in my opinion.
What I have experienced to be more of a factor on the quality of your vital software than anything is your corporate culture, however, I’m sure you can succeed with more autonomous teams and with dedicated departments alike, but to do so, the single most important factor is that you let your engineers and their quality decide when things are ready. Your entire organisation needs to understand that no matter what level of CEO you are, your opinion doesn’t matter if the engineers tell you something isn’t safe. And you need to foster a culture where your engineers will actually tell you that things aren’t ready without any sort of incentives to lie or move too fast. Which is incredibly hard to do.
I suspect that AirBus is simply better at this than Boeing. With the amount of scary stories to come out of Boeing in recent years, it sort of looks like Boeing has become a place where money matters more than anything else, so much so, that quality product aren’t as important to them as they once were. Which can frankly happen to any organisation and Boeing can also find its way back from there.
But really, if that happens to an organisation where it costs lives it’s the responsibility of the government to shut those companies down with regulations. Which is something the US seems to struggle with, and many Americans will likely even find this statement sort of appalling.