It's not just that the person would be expensive. Systems like that require system specific knowledge. So it's possible that it would take an outsider 3 months of study to get to the point where they can fix an issue properly in 5 minutes.
You can't make a baby in 1 month with 9 mothers. Some tasks just have an upfront cost and SOME IT automation jobs are like that.
And yes, you can try and do bodge job after bodge job "just to keep it going". And that works for some time. But eventually the small mistakes end up causing large outages. And then you need someone that can piece together how the small issues cause big outages.