I am comparing it with a skilled cousin or another employee, as a thought exercise.

Your personal incredulity aside, if you write code and create a PR, you're expected to know and understand the code you're writing, and you're expected to have done at least some means of verifying correctness. If you can't do that, ask for help from someone who can, earlier in the process, and/or give the task to them for normal prioritization.

Your example reveals a common organization smell: work not going through the normal process for prioritization and planning. If you've done that, and the work is deprioritized, that's because the company has decided that your thing isn't as important for engineering to do. Get over it and be patient, or ask a mentor for help selling the business on the value of your thing. Creating a PR bypasses that process and burdens engineering with more work (having to understand and rework slop) than if engineering had coded the thing to begin with.

tl;dr: if a company is internally strategically unaligned, organizational dysfunction is bound to follow