The biggest workplace challenge I face that resurfaces frequently, is the sway from the DevOps principles, frequently due to certain interest reasons. I think a good principled governance system may address issues like this, but I have yet to learn a good and practical one. Any ideas?

This is a very hard topic.  If the team is continually drifting back to older practices, then it is typically due to misaligned tooling or lack of buy-in from the whole team.  My experience has been it is often best to work with leadership to identify what is most important to them.  Then identify proxy metrics for showing how your team aligns with those priorities.  Capture the metrics while using the old practices, then do the same with the DevOps practices.  Your retrospectives are a great time to have the team view and reflect on how well the metrics are reflecting the story you are trying to tell - and how well the team's performance is addressing the priorities.  

TL;DR - Meeting those who object with metrics and aligning the measurements with top-down objectives has been the most effective means to help correct alignment.

David Greenstein