Too much critrical software in such modern systems, while most of the talented guys prefer to go to googles, apples, yahoos, etc.
The guys at google, apple, etc aren't that talented. Most of Google's software is permanently in beta and the 'rocket scientists' at Uber have so far managed a self-driving car that can knock down cyclists and which they tried to claim wasn't self-driving to get round Californian law. Apple are responsible for iTunes which is basically a virus with mouse support.
It may just be that writing critical software that doesn't have glitches is really really hard.