system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why is US postage the same for 2 miles and 2000 miles?
gpt
The transit distance isn't the main cost, it's the overall infrastructure of the postal system. 

Whether or not a single piece of mail gets sent from Orlando to Miami or from Orlando to Seattle, the mail truck from Orlando to Miami and the plane from Orlando to Seattle are still going to make that trip every day. As are thousands of other vehicles going on routes. That extra mail won't add a fraction of a cent to the operating cost of either vehicle, but in the aggregate they do cause wear on the equipment, and the equipment requires maintenance, and people to operate it, and other expenses that generally get incurred in running the postage system.

Where you start to see higher rates are in places where that isn't the case - either a courier service that charters a vehicle to deliver something, large deliveries that require special trips, things like that - that is where you get more expensive delivery fees.