Originally Posted by
Efrem
In many, perhaps most, countries, passengers coming off international flights have to pick up their bags at the port of entry in order to clear customs. They then re-check their bags at a transfer desk outside the customs hall. Since nobody forces anyone to re-check bags - in fact, there is generally no way to tell connecting passengers from those who have arrived at their destinations - international arrivals have an automatic short check whether they want it or not.
There are some forced rechecks due to airport layouts- if your international flight comes into E Concourse in ATL, there is no direct landside exit at that point- you claim bags, do the customs formalities, and then have to give them back to the airline to have them sent to a landside carousel because the passengers need to go through a full TSA security checkpoint and then through the airside area proper before they can collect bags and exit the airport. And getting a bag labeled for a connecting flight retagged to get sent to ATL landside is only going to work if it looks like you're at risk for an immediate medical emergency.
(On the other hand F Concourse in ATL has a perfectly nice direct exit to landside from immigration.customs)