system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why does it cost upwards of $50 to ship from USA to Australia, yet I can get the same thing from Amazon with $10 shipping.

Looking to buy a few things that I can't get from Amazon and the shipping is upwards for $50 for something that is $20, yet I bought something on Amazon last week that was significantly bigger and heavier and it only cost $10 shipping.
gpt
Amazon ships in bulk, literally by the truckload/shipping container, which saves both you and them money. The other shipper probably doesn't have the kind of volume to negotiate the same level of shipping discount.