Can't you automate around this edge case that we told you during planning could never happen due to controls on our end?

That's easier for us than sticking to our word.

What do you mean that it was a key requirement of your design, like you told us in advance?

I'm currently in a software development project which was handed over to a different department with little software development expertise, and fucking hell, I hear this so often.

Can't you just run the tests against against a database like normal? Why do you need to automate the setup of this database? (I do not know what "normal" means, they did not elaborate.)
Can't you just switch over all the code to go directly against the database rather than also supporting in-memory.
And then five minutes later: Can't you just hook up the database connection where we need it and use in-memory for the rest?

Like, I'm trying to appreciate the critical questions, because hey, maybe there is something I'm missing. But always this "just", and them being dissatisfied when you tell them it doesn't make sense or would be more work, that's what kills me.