On a QF flight one time, the FA got distracted somehow when doing the final floor check and missed a bag placed under the seat in an exit row. Mistakes do happen, is all I put it down to. If any staff member ever claimed that these types of mistakes *never* happen, they are lying.
I'm always amused by the Pilot's genuine surprise to think that QF staff don't try to get away with things that may not necessarily strictly follow procedure. It may not be their own personal experience, and considering they're a pilot, it's not like other staff are going to share their experiences as to what they attempt to get away with. The crew, including CSMs represent a wide range of people and personalities, and are not all perfect cookie-cutter staff.
In my experience, the delivery of the Exit row safety briefly has been delivered with a wide spectrum of enthusiasm, care-factor and attention to detail, from strict-as-anything through to it's-been-mentioned-to-cover-the-legal-requirement, but it has always been delivered.