During the first few years, countries have an easy time nominating places with high degree of success, since their initial proposals are the most famous and most well-known places that are treated as benchmarks. This means that the nomination is like a formality, it's just a matter of putting together all the infos which are already available from expert studies and greater visibility and familiarity among the evaluators.
I am not sure that either the list of early inscribed sites or the available documentation fully supports this thesis!! Consider
1978 - Wieliczka Salt Mine, Nahanni,
1979 - Madara Rider, Thracian Tomb of Kazanlak, Rock Hewn Churches of Ivanovo, Boyana, Vezelay
1980 - Dormitor, Tiya, Bosra, Roros
1981- Niokolo-Koba, Quirigua, Head Smashed in Buffalo Jump
1982 - M'zab, Tai NP
In fact the very early years provided an extremely
easy ride for gaining inscription for sites which can by no means be called "the most famous and most well known places that are treated as benchmarks". I am not necessarily saying that the above sites have no merit but they, and many others from those early years, are hardly the material for "world class benchmarking" and some might even struggle to justify their OUV today.
Nomination was almost a formality not necessarily because the sites were unarguably famous etc but because the standards of evaluation and the documentation required were so much "lighter". I might suggest that Egypt would find it difficult today to get The Pyramids inscribed! For a start they would have to produce a good few gB of documentation and I doubt if their buffer zones, management plans etc would stand up to scrutiny (probably quite justifiably so too!)
The reason why it is more difficult to get sites inscribed today is not all because the barrel is being scraped for less well known places which are, as a result, less well looked after/studied than the famous sites inscribed earlier. If Myanmar ever gets round to nominating Pagan - a site which surely is the equal of any on the list, the degree of scrutiny and the requirements they will have to meet will be far greater than any site, famous or not, had to face in the first 10-15 years or of the scheme. One AB review I find particularly amusing from those early years is that for the Wurzburg Residence (inscribed in 1981). ICOMOS states "The inclusion of Wurzburg Residence in the WH list constitutes a measure wihch is so clearly desirable that the Federal Republic of Germany does not require a lengthy justification" - so no worries about management plans, authenticity, pressures from development/environment or tourism, ownership, legal protection, disaster plans, etc etc there then! Countries could nominate sites knowing that this was the level of "justification" required!
On another matter. Hasn't Egypt "missed out" a fair number of its potentially inscribable "pharaonic" sites between Cairo and Thebes, Thebes and Aswan and in the desert oases?
e.g Abydos, Armana, Dendera, Beni Hasan, Edfu, Kom Ombo, Fayoum, Kharga etc most of which (and many others) are queuing on the Egyptian T List! Many are the equal in magnificence of archaeological sites inscribed elsewhere around the World - but i guess one can just have too much of good thing from one country! Egypt doesn't seem to be very active at bringing them forward as far as I know?