When flying from Canada to the US, US immigration occurs in Canada. This is known as "pre-clearance" and allows the plane to land in the US as if it were a domestic flight - including allowing flights to US airports that do not have immigration facilities.

The W3C DNT spec explicitly says that a browser should not set this by default, yet Microsoft is completely ignoring the spec and turning it on by default. What Yahoo is doing it 100% correct - it's the only right answer to Microsoft completely ignoring the DNT spec, both in it's intent as well as it's actual words. Every other major web property WILL do the same. Apache already has a patch to ignore DNT from IE10, now Yahoo is doing the same, and the rest will follow.

This makes perfect sense. These machines are slower than the new one, so they are moving them to smaller airports where there are less people, and shorter lines for security.