Is there any notification via email or SMS? "Decades" suggest that they are just physical lockers that you have to go and manually check for mail. We have these too in rural areas, where delivery to every single farmhouse is too expensive and time-consuming. But modern parcel lockers are different. They are networked computers connected to solenoids that operate door locks. You get a code via mail or SMS when a parcel arrives, and when you go pick it up, you enter the code and a door automatically unlocks and opens.
Sending a parcel is similar: you can prepare a shipping label at home and print it out. When you arrive at a locker, you just scan label's barcode, a door opens, and you pop your parcel in there. Or you can prepare the label at the parcel machine, it will print out a sticker for your parcel. Stick it on, scan the code, door opens, put your parcel there.
A standard parcel locker looks like this: https://i.imgur.com/X5Gj4JQ.jpg
Different size doors are for small / medium / large parcels. Center section has touchscreen, payment card reader, barcode scanner and a printer for shipping labels and receipts.
Such parcel lockers have been around for approximately 15 years, but usage exploded somewhat later.