Can the criteria be less vague & the submissions be fair

I have submitted various locations as stops, one accepted but no stop or gym added to game (if it’s because it’s too close to a current gym/stop, I’d like to know why it’s not added despite various other gyms/stops being very close together including added ones in other locations). I have also submitted stops that follow criteria, including a post box as a test as I see lots of post boxes added left, right & centre. This, as well as various others rejected about 6 months after submitted. It seems those in prime locations can submit whatever they want & accepted, those in rural areas (that I believe this system is there to help with) seem to have everything rejected
Answers
Regular post boxes are mass produced and should not be accepted. (https://community.wayfarer.nianticlabs.com/discussion/107/u-k-postboxes/p1)
With that being said I agree that some criteria seems a bit vague. I also have had nominations not accepted even though I think they should be. More feedback on rejected nominations, and on disagreements in wayfarer, would (hopefully) result in better nominations.
I used that as an example as there’s tonnes of generic postboxes everywhere in the game, I submitted a wedding venue/restaurant that was rejected despite other restaurants & wedding venues being accepted, it seems hit & miss
In the UK, a very small and limited number of postboxes are considered eligible, but none of the ones that were commissioned under the current monarch would be allowed. Ones marked with a "EIIR" for "Queen Elizabeth II" are deemed "common". If you can find one as rare as a "King George" marked with "GR" then those are uncommon enough to qualify.
*this is a UK-ism, and unless enormously unique, post/mail boxes won't qualify anywhere else.
GR and GRVI do sometimes get accepted, although I'm not sure they generally really meet Niantic's 'historically significant' guidance. Victorian and Edwardian ones generally go through (although again probably only some should really be accepted).
It relates to Casey's answer regarding the iconic Red Telephone Boxes. Some variations are uncommon enough to become eligible, some just ... aren't.
https://community.wayfarer.nianticlabs.com/discussion/5611/red-telephone-boxes-in-the-uk