[cweagans]

Without legally imposed duty of care, the only thing that can be done to draw a line in the sand is to commit (collectively) to maintaining a reasonable level of professional practice.

Simply do not entertain probing and meddling. "It's going to take a little longer because the software is complex and it takes some time to untangle it" is all you need to say. Whether you refactor/test/document it in the process of understanding it is irrelevant.

[selfhoster11]

That won't work. As I said, for developers, this is a Prisoner's Dilemma scenario. It simply takes enough defectors to fill jobs at companies that don't care about quality, and you lose any collective power you had as a group.