Actually its basically the opposite. The US rules say 'no' liquids can go through security over 100ml. In the US, all airports and all flights are held to this standard and it is enforced at the checkpoint. This allows the 'opportunity' to buy water airside before boarding the plane.

In most other countries, they don't subject their passengers to these stupid, useless, and arbitrary rules and so the screening is not performed at the normal checkpoint. They usually have the separate screening you appear to be experiencing that occurs at or near the gate for US departing flights. that way they don't have to trouble other pax with our stupid rules.