I think the requirement is basically only in areas that have high rates of people complaining about things not turning up, and even then, Amazon doesn't really seem to care.

For a while, my home had very poor labeling of its address on the building, and getting anything delivered was always a crapshoot of drivers giving up and just picking a random location to leave it instead. They would happily take photos of them having left it at a home that was not mine, not remotely mistakable for mine, and Amazon didn't treat that any differently from the cases where there were no photos at all.