The issue is that the differences on some products amount to thousands.
$2,000 USD difference on a 1DX
$3,000 USD difference on a 200-400
$4,000 USD difference on a 600 II and 800
And the USA warranty period is only one year. Quite brief, relative to the reasonably expected useful life of the gear involved, much less the cost and sophistication of the gear listed above.
On the other hand, BECAUSE of the tremendous cost, precision, and computer circuitry involved in the products above, it can be very expensive NOT to have a warranty during the initial year when the products are delivered.
Cameras are portable items, not houses. Even though these cameras and lenses cost more than I paid for my first house, unlike my house, cameras are used more often when traveling. And that includes the big cameras and lenses listed above, which are the tools of choice for wildlife and sports photographers throughout the world.
Canon's camera and lens warranties should be honored world wide, period.