Maybe part of it is due to this
https://en.wikipedia.org/wiki/Universal_Postal_Union
I remember reading a few years back that when mail flow between countries was relatively equal, this system worked.
Now that we buy by email and all "physical" deliveries come from overseas, the system at our end just bleeds.
ie ask yourself how you can get "free" delivery on ridiculously lowly priced items from China?????
someone has to pay somewhere, so i guess they are making it a bit more transparent.
Andrew