A question for English native speakers or people who live in English-speaking countries:
If there are such objects for parcels in your country, what are they called?
parcel box?
parcel boxes?
parcel delivery locker?
parcel locker?
parcel lockers?
parcel machine?
parcel pickup station?
other?
Hi, I and everyone I know call them Parcel Lockers because they are a bank of locked containers so amenity=parcel_locker. There is currently a vote underway on a proposal to tag them as amenity=parcel machine, but are they really machinery, there’s no machinery involved. Anyway please see:- https://wiki.openstreetmap.org/wiki/Proposed_features/amenity%3Dparcel_machine#Voting
I suggested =parcel_machine and =parcel_terminal to OP who wants them to not be limited to lockers, plus asking to sub-tag its locker structure and secondary locker function. They are listed as synonyms in the proposals. Vending boxes come in many forms too, yet all of them are =vending_machine. “Machine” is not limited to industrial machinery. The electronic control and electromagnetic (perhaps even electromechanical) lock mechanism are quite “mechanical” already.
If vending_machine is correct, why is parcel_machine wrong?
Probably for the same reason that in Polish we don’t call it “maszyna do paczek” 
You appear to be expecting logic and consistency from the English language?
Historically vending machines had quite complex mechanical parts to deal with separating out coins and delivering change which I suspect determined the naming.
The Amazon/UPS parcel lockers work in a way very similar to left luggage lockers at railway stations, so no surprise these are called parcel lockers.
Hi, The proposal to describe these things as amenity=parcel machine has been dropped due it seems to some opposition. A new vote is underway on a proposal to describe these things as amenity=parcel_locker.
Please see:- https://wiki.openstreetmap.org/wiki/Proposed_features/amenity%3Dparcel_locker