Funny you used the word "developer", and I used the word "engineer", because that distinction is critical. A brick layer is not a civil engineer, and is not signing off on a construction project. Likewise, the developers banging out tickets don't have to be software engineers who sign off on a software project.

In the Horizon case, I'm thinking of people like Gareth Jenkins. He was the guy who designed the system, and also one of the expert witnesses you mentioned. He's the one who should be held to the standards I'm talking about.