Seat belts are a listed part. To give some credence to this look at the way it unlatches from the buckle. In the average "spam can" when you pull the release it releases at 45 degrees, because that is what the FAA require. When you next get on a UK airliner note that it doesn't release until 90 degrees, as that is what the CAA specify!
Given that these rules are in place for something as trivial as how to undo the buckle, I imagine that the rest of the belt is also subjuect to the usual maint. rules.