As I understood the product, your "amazon locker" was your local 7-11. I imagine there's not a major difference in efficiency between having your "amazon locker" at 7-11 along with your conceptually-different "ebay locker", vs having your unified "postal services locker" at 7-11.
In the UK it's both [1]. There's big yellow metal boxes [2] and if there isn't one in the area they deliver to the "7-11" who is probably providing Collect+ [3] type service.
7-11 has been acting as a logistics and pick up service for ecommerce deliveries in Japan since the 1990s iirc. But 7-11 is way more ubiquitous in Japan.
