Show the gold efficiencies of some tier 3 items and how they are so much better. Being 142% efficient is extremely good.
For example, Phantom Dancer is 118% efficient and it's almost just a ball of stats, the only thing unaccounted for is ignoring unit collision, which would have to be worth 700g just to match Atma's efficiency when used by a 3000hp champ, and that is again ignoring the fact that Atma's builds from a gold gen item. I seriously doubt ignoring unit collision is worth the 700g, and even if it is that would by your standards still leave PD as being a terrible item.
PD is a terrible item, that is why static shiv is bought whenever pd isn't crucial, it is just a big ball of stats, it just happens to be a big ball of the correct stats for a certain champ type, which makes it useful, basically PD > adc as atmas > Garen. Not too mention no champ naturally has 3k hp so you are spending more gold before it is 142% efficient
IE and deathcap are the kings of gold efficiency. Stats alone make up more then the cost and with the passives buying more ad or more ap respectively they go into the 4.5k-5k range of value with just your base AD or for deathcap your dorans and runes.
You can actually look up an items base gold efficiency on the lolwiki so I'm not going to bother doing that homework for you.