Here's another one. Engineers also can't stand broken flow. If you'd ask me "hey, can you move that button by 3px?", that's pretty much equivalent to asking me - "hey, can I waste some of your time?". But if it actually fixes lag or broken flow, this is significant. And any good engineer will be happy to help that fixed.
Where I work, pixel alignments and gaps are generally explicitly indicated in the design spec. If the code is not following the spec, its definitely the code's fault. If the spec is found to be wrong after implementation, then first fix the spec then ask for the code to be synced.
There is a whole class of people who are good at red lining and doing design QA; in a larger company, it might not even be the designer, but the design QA engineer, submitting the bug report.
