Asking why why why why

The famous Toyota four whys are a good rule. Take for example the critical bug we had in the latest release.

1. Why?
Well, it wasn't tested

2. Why wasn't it tested?
We tested it manually at the beginning of the last week, but not after the final critical check-ins.

3. Why manual test?
There are no automatic tests on that feature.

4. Why???


And here we come to the core of the problem. The problem is that we lack automatic tests on critical functions. And even if we fixed the bug now, we're open for the same bug next month. So, we didn't fix the problem. We fixed the acute bug. And that is the problem...